Article by:

Mike Diamond
Error-ref.com

Compiled by Mike Diamond

This checklist is my attempt to compile a comprehensive listing of all known variety and error types, subtypes, and associated effects. It is updated periodically to reflect the current state of knowledge.

While the traditional planchet-die-striking method of classification hasn't been completely abandoned, it has been absorbed into a much more detailed and precise taxonomy. This is intended to reflect the numerous steps (and missteps) in the minting process that generate the great diversity of anomalies presented here.

Many of the categories will be familiar to veteran collectors. Others will perhaps be dimly recalled, while others will be unfamiliar. Many of the more obscure error types have been covered in detail in articles published in Errorscope ("ES"), Coin World ("CW"), and Coin Week ("CWK").

I have tried to restrict this checklist to basic error/variety types and subtypes. Combination errors have been kept to a minimum. Had I attempted to incorporate all conceivable two-error combinations, this would have generated almost half a million entries. That would have been both unwieldy and unnecessary.

 

ES=Errorscope

CW=Coin World

CWK=Coin Week

Part I. Design Subtypes

 

Patterns and Prototypes (accidental release)

 

1916 Winged Liberty ("Mercury") dime patterns

1971-S Eisenhower dollar prototype (CW 9/29/08)

2000-P Sacagawea "Cheerios" dollar

 

Mid-year design modifications

 

Type 1 and Type 2 1913 "buffalo" nickels (raised vs. recessed "FIVE CENTS")

1917 Standing Liberty quarter with breast covered or uncovered

Change from 1960 small date to large date cent

1853 Seated Liberty dimes and half-dimes, with and without arrows

 

Conceptual design flaws (foul-up in design or in translating design to master hub or master die) (CW 11/15/21)

 

Misspellings (foreign only) (CW 1/25/16)

Inaccurate design

Italy 1000 Lire with outdated map borders

Canadian $5 Olympic Coin.Runner with two left feet

1817 large cent with 15 stars (possibly done intentionally as a political statement)

1828 half cent with 12 stars (possibly done intentionally as a political statement)

 

 

Mistakes during design modification (CW 4/18/16)

 

2007 Mexico 10 pesos with reversed dentils

2008 Chile 50 pesos with country spelled "CHIIE"

 

 

Unauthorized strikes and unauthorized issues (CW 1/20/14)

 

1913 Liberty Head Nickel

1954 Mexico 5 centavos (small size)

 

 

Part II. Die Varieties

 

Reduction lathe doubling (master hub doubling)

 

Master die doubling (master die with a doubled die variety) (CW 7/27/20)

 

Broken hub (chipped hub) (CW 12/23/13, 5/21/18)

 

Crumbling hub (CW 3/25/24)

 

Hubbed-in debris (CW 5/27/13, 1/17/22)

 

Broken punch

 

Damaged punch

 

Defective punch

 

Longacre doubling (probably impressions of punch shoulders)

 

Doubled dies (incl. tripled dies, etc.)

 

Rotated hub doubling (Class I) (CW 8/8/16)

1872 Seated Liberty dime with 175 degree rotation (ES July/August 2003; CW 2/10/03)

Distorted hub doubling (Class II)

Design hub doubling (Class III)

Offset hub doubling (Class IV)

Pivoted hub doubling (Class V)

Distended hub doubling (Class VI)

Modified hub doubling (Class VII)

Tilted hub doubling (Class VIII)

Single-squeeze doubled dies (often attributed to Class VIII) (CW 2/14/05, 9/12/05)

Peripheral doubling (CW 8/2/04)

Centrally-located doubling (CW 3/21/22)

Weaker impression hubbed last (e.g. 1963-D cent) (CW 6/14/10)

Centrally-located doubled dies (CW 4/15/19)

Rotated

 

Weak or incomplete hubbing (always part of a doubled die)

 

Tilted hubbing (always part of a doubled die)

 

Misaligned hubbing (CW 5/30/22)

 

Repunched dates (ES July/August 2012; CW 12/14/09, 7/11/16)

 

1956-D cent with repunched 5 (controversial) (CW 9/20/04, 7/16/12)

1957-D cent with repunched 7 (controversial)

 

Re-engraved dates (on master die or working die)

 

Blundered dates (on master die or working die)

 

Misplaced dates (e.g. digits in denticles) (CW 4/21/03)

 

Misplaced mintmarks

 

Phantom mintmarks (working hub has mintmark incompletely removed)

(e.g. faint D and S mintmarks in cents from the late 1990s)

 

Dual mintmarks

 

1980 D & S cent (recently delisted)

1956 D & S cent (controversial)

 

Horizontal mintmarks (inevitably repunched)

 

Tilted mintmarks (punched-in at an angle) (CW 7/28/14)

 

Rotated mintmarks (CW 7/28/14)

 

Inverted mintmarks

 

Deeply-punched (high-standing) mintmarks (CW 9/29/14)

High-standing D-mintmark (1987-D, 1988-D, and 1989-D cents)

 

Weakly-punched mintmarks

 

Repunched mintmarks (CW 1/20/20)

 

Overlapping mintmarks

Mintmarks totally separated

Two different fonts

Large over small mintmark

 

Overmintmarks (e.g. 1944-D/S cent)

 

Other repunched or re-engraved design elements

Denomination

Letters

Assay value

 

Omitted mintmarks (e.g. 1982 no-P dime)

 

Omitted dates (foreign only) (CW 4/28/14)

 

 

Other omitted design elements

 

Large over small mintmark

 

Different mintmark styles and sizes

 

Overdates (CW 1/23/17)

 

Caused by repunching

Caused by second hubbing with die of different date (Class III doubled die)

Caused by grinding off earlier design and rehubbing or repunching (CW 1/23/17)

 

 

Dual Dates (earlier date faint)

 

Caused by erasing earlier date on working hub

Caused by removing earlier date from working die and re-hubbing

(e.g. 1975 Bahamas 5c with faint date "1973" on opposite face)

 

Wrong dates

 

Date later than final date of issue (e.g. 1913 Liberty Head nickel)

Date earlier than first date of issue (e.g. 1954 Mexico 5 centavos - small size)

Wrong digits (e.g., 1393/1893 Peruvian peso)

Transposed digits

 

Blundered dies (various types) (CW 8/18/08)

 

Special Finish Errors (Proofs, Mint Sets, Special Mint Sets, Satin Finish, etc.)

 

Frosting slop-over (proofs)

Offset frosting (proofs) (CW 2/21/11)

Design removed by proof polishing (CW 2/21/11)

Field lowered by proof polishing (CW 2/14/11)

Frosting in wrong place

"Frosted Freedom" $50 and $100 platinum coins (CW 8/1/11)

Frosting omitted

Stencil outlines (CW 2/18/13)

Incomplete proof laser frosting (CW 9/12/16, 9/6/21)

 

Design Extension Dimples (CW 4/18/2011)

 

Edge lettering font variants

 

Presidential dollars (4-5 types) (CW 10/18/10)

 

Hidden initials and symbols (CW 5/18/20, 2/2/24)

 

Applied to working die or master die

1973 and 1974 Mexico bronze 20 centavos

1984 Mexico 1 peso

Applied to working hub

2023 "extra V" cent (CW 3/27/23)

 

Part III. Die Installation Errors

 

Mules (ES May/June 2010)

 

Wrong hammer die

1995 cent/dime mule

Wrong anvil die

1993-D and 1999 cent dime mules

Wrong hammer and anvil die (CWK 8/20/25)

Maryland quarter on Sac planchet in Sac collar (3 specimens)

Two anvil dies

Two-tailed clad dime (1 known specimen, probably from 1965)

Two-tailed clad quarter (4-5 known specimens, probably from 1965)

1982 Jamaica cent with two obverse faces

Two hammer dies

1859 Indian cent with two obverse faces (unique)

!981-P quarter struck by two obverse (hammer) dies (CW 7/22/24)

Two obverse or two reverse dies (die setup unclear)

2000-P nickel with two obverse dies (CW 6/26/17)

Two different countries

(1967) Bahamas 5c/New Zealand 2c mule

Different denominations

Washington 25c/Sacagawea $1 mules (16 specimens, 3 die pairs)

Mule die larger than normal die and collar

1995 cent/dime mule

Mule die same size or smaller than normal dies and collar

(All known U.S. mules employ dies of different sizes)

Temporal mule (dies from different years) (CW 1/20/14)

1959-D wheatback cent (unique)

2000 Macedonia 1 denar muled with obverse die used in prior and later years

Commemorative 1992 Canadian quarter muled with 1993 reverse (CW 9/17/01)

Temporal/transitional mule (dies from different years with change in planchet composition) (CW 1/20/14)

1942-S silver alloy five cent coin with small S-mintmark to right of Monticello (unique) (CW 5/9/16)

1993 bimetallic Russia 50 roubles (St. Petersburg mint set only) (ES March/April 2010; CW 3/20/17)

Regular-issue die muled with commemorative die

September and November 1999 Canadian quarters

Regular-issue die muled with government medal or token die

2000 Canada "map mule"

Regular-issue die muled with private token, medal, or nonsense die (ES Jan/Feb 2008; CW 11/25/13)

Mules involving pattern dies (various types)

Normal die paired with pattern or prototype die (CW 2/2/04)

Collar mule (collar from different denomination of same or similar size installed)

Lettering die mule (mismatch between edge lettering applied before or after strike and the design shown on the obverse and reverse face)

Presidential dollar with wrong date on edge

2009 Zachary Taylor dollar with 2010-D edge inscription (CW 2/22/10, 3/1/10)

2007-D Sacagawea dollar with Presidential dollar edge lettering (CW 7/9/12)

Pseudo-mules (3 pathways) (CW 4/25/11, 3/19/12, 4/23/12, 12/11/17, 12/17/18, 2/22/21, 12/12/22, 1/15/24)

One U.S. two-tailed quarter may belong in this group (CW 11/27/04; 8/27/12)

 

Mismatched business / unfinished proof dies

 

1999 $5 and $10 gold eagles struck with unfinished proof dies (W-mintmark)

1998-2000 business strike cents with proof-style reverse ("wide AM")

1998-S and 1999-S proof cents with business-style reverse ("close AM")

1956 -1964 quarters with "Type B" proof reverse

 

Finished proof die matched with business die

 

Early 19^th century examples (CW 8/20/12)

 

Transitional reverse dies (minor temporal mismatch or "mini mule") e.g.:

 

1939 nickel with reverse of 1938

1940 nickel with reverse of 1939

Proof 1940 nickel with reverse of 1938 (CW 4/19/08)

1964-D quarter with the "Type C" reverse of 1965

1988 cent with reverse of 1989

1992-D cent with "close AM" reverse

 

Inverted die installation (not an error) (CW 2/15/10, 7/22/19, 1/6/20)

 

Older issues struck with inverted dies (e.g. buffalo nickels and Mercury dimes)

Re-introduction of inverted dies (beginning 1989) (CW 12/4/23, 12/11/23)

Saddle strikes produced by inverted dies (CW 9/13/10, 9/19/16)

 

Late use of traditional die setup (CW 6/25/18, 9/30/24)

 

Fixed rotated die errors (see Part VI)

 

Collar installation errors

 

Smooth edge instead of reeded edge (and vice versa)

1863 Indian cent with reeded edge (CW 6/3/2002)

Smooth edge instead of edge design (and vice versa)

Reeded edge instead of edge design (and vice versa)

Segmented proof collar with segments out-of-order (CW 4/7/08)

2007-S proof Presidential dollar with segments arranged in incorrect sequence (CW 4/7/08)

 

Use of flat, featureless dies (CW 6/30/14)

 

Use of cancelled and defaced dies (CW 5/12/14, 5/8/17, 12/31/18)

 

Cancelation overstrikes (coins overstruck by canceled coin, pattern or test dies) (CW 5/8/17, 5/24/21)

 

Defaced die overstrikes (coins overstruck by defaced dies) (CW 5/12/14; CWK 6/20/25)

 

Design/composition mismatches (CW 2/10/20)

 

 

Part IV. Die Errors

 

Reeding vs. no reeding varieties (foreign only)

 

Concentric lathe marks (ES Nov/Dec 2003; CW 3/12/8)

Especially common among 1996-D cents

 

Die rings (tiny circles, semicircles, and spirals) (CW 2/20/17, 1/18/21, 6/13/22)

Centrally-Located

Uncentered

 

Rusted die (CW 12/1/08)

 

Excessively deep rim gutters

1991 cents

 

Rockwell test mark left in die (hemispherical bump seen on coin) (ES July/Aug 2006)

 

Vickers test mark left in die (pyramidal bump) (CW 5/15/17)

 

Collar manufacturing errors

 

Wide collar (ES Nov/Dec 2002; CW 5/17/10)

Created by improper machining or improperly machined broach

Created by use of wrong broach

Improper use of correct broach

Widening due to wear

Widening due to 3 or more vertical collar cracks and associated expansion (CW 5/17/10)

Abnormal reeding

1921 Morgan dollar with infrequent reeding

1924-D Mercury dime with infrequent reeding

2015 American Eagle 1/10oz gold $5 bullion coin with narrow reeds (CW 7/13/15)

Low, narrow reeds caused by truncation of ridges on collar face (ES March/April 2010; CW 1/25/10, 4/16/12)

1964-D 25c

2008-P New Mexico 25c

 

Hub Retouching

 

Channeling (hub retouching affecting master and working hubs from 1920s to 1940s) (CW 7/23/12)

Re-engraved master hub (CW 1/1/24)

 

Die retouching (CW 5/30/16, 9/30/19)

 

Re-engraved "AW" mintmark on 1944-D half dollar (CW 2/2/04, 2/16/04, 3/1/04)

Re-engraved tail feathers on business-strike 1957-D quarter

Re-engraved front of Lincoln's coat (1953 proof cent)

Re-engraved working dies and hubs on Lincoln cents (CW 9/30/19)

Re-engraved queue on 1952 - 1954 proof nickels

1938 proof nickels with re-engraved letters and design details (ES Jan/Feb 2009)

 

 

Die damage (ES, Nov/Dec 2004, Jan/Feb 2003; CW 5/21/12)

 

Die dents (ES, Nov/Dec 2004, July/August 2005, Nov/Dec 2005; CW 9/15/03, 12/22/14, 3/28/22, 7/31/23, 10/21/24)

Die scrapes (CW 4/23/07, 3/19/19, 3/7/22, 4/8/24)

Accidental die scratches

Die gouges

Impact scars

Accidental die abrasion (CW 9/8/14, CW 12/16/19)

Intentional die abrasion ("die polishing") (CW 3/29/10, 5/31/10, 9/8/14, 3/20/23)

Heavy die scratches

Thinning and loss of design elements

Abrasion affecting entire die face

Localized abrasion

Defects related to die polishing

Over-polished proof and SMS dies (CW 2/21/2011)

Trails and Wavy Steps (ES July/Aug 2006, Sept/Oct 2006, Nov/Dec 2006, Jan/Feb 2011; CW 3/8/10, 7/ 17/17, 7/30/18)

Localized removal of field from proof polishing (CW 2/14/2011)

Die attrition errors (ES May/June 2003, March/April 2005, March/April 2009; CW 1/4/10, 12/24/12, 4/14/14, 11/4/19, 7/3/23, 10/16/23, 2/19/24)

Other forms of peripheral die damage (ES March/April 2005, CW 8/9/21, 3/14/22)

Catastrophic die damage (ES March/April 2002; CW 9/15/03, 9/12/11, 9/19/11, 5/20/13 10/27/14, 6/19/17)

Canceled or defaced dies (foreign only) (CW 5/8/17, 12/31/18)

1994 Hong Kong bimetallic 10 dollars

Egypt 25 piastres struck by defaced 50 piastres dies (CW 5/12/14)

1966 Bolivia 10 centavos struck by pair of canceled dies (CW 5/8/17)

Chilean test dies with concentric cancellation pattern struck over struck foreign core (CW 5/8/17)

Rockwell test mark in die (CW 5/15/17)

Vickers test mark in die (CW 5/15/17)

Die rings (tiny rings, semicircles, and crescents) (CW 2/20/17)

Centrally-located

Offset

 

Hubbed-In debris (CW 5/27/13, 1/17/23)

Collar damage (ES March/April 2010; CW 1/25/10, 4/16/12, 6/17/19)

Horizontal abrasion (CW 1/25/10, 4/16/12)

Vertical abrasion (CW 6/17/19)

 

Deformed collar (CW 12/28/20)

 

Clashed dies (ES March/April 2002; CW 3/22/10, 4/30/12)

 

Multiple clash marks (including "chatter clash") (CW 6/25/12, 11/11/19)

Raised clash marks (CW 8/11/14)

Double clash with reciprocal counterclash (Type 1) (ES Nov/Dec 2004; CW 12/13/10, 7/29/19, 11/11/24)

Misaligned die clashes (ES May/June 2004, July/August 2004; CW 6/25/12)

Horizontally misaligned die clash

Vertically misaligned (tilted) die clash (CW 1/3/11, 5/9/11)

Pivoted die clash

Radically misaligned, rotated, pivoted clashes - produced at installation? (CW 7/12/10, 12/31/12, 5/27/19)

Co-occurrence with conventional clash (CW 8/17/15)

Rotated die clash (CW 1/22/18, 6/26/23)

Combination clashes

Mule clash errors, e.g. (ES, July/August 2002) (CW 11/17/08, 8/13/18, 8/20/18, 4/8/19)

1864 2c reverse die clashed with Indian cent obverse die

1857 1c obverse die clashed with Seated Liberty 50c obverse die

1857 1c reverse die clashed with Seated Liberty 25c reverse die

1857 1c obverse die clashed with Liberty $20 obverse die

1857 Seated Liberty 25c reverse die clashed with 1857 1c reverse die

1870 Shield nickel obverse clashed with Indian Head cent obverse

1999 cent reverse die clashed with another cent reverse die

Floating die clash (collision with die fragments) (ES, May/June 2002, May/June 2005; CW 7/19/10)

Superclash (full reciprocal design transfer) (CW 3/22/10, 4/30/12, 10/22/18, 9/9/24)

Circumferential clash marks (CW 12/10/18)

Grease-enhanced clash marks (CW 10/16/17)

Associated with weak strikes (CW 12/2/19)

Clashed die progressions (5/15/23)

Collar clash (CW 6/11/07, 2/24/22)

Hammer die

Anvil die

Inverted die setup (uncommon)

Traditional die setup (extremely rare) (CW 10/30/23, 12/18/23)

Floating collar clash (CW 4/17/17)

Misaligned collar clash (CW 2/13/23)

 

Die damage with design transfer

 

Floating die clash (ES, May/June 2002, May/June 2005; CW 7/19/10)

Exogenous floating die clash (CW 6/20/22)

Floating (Type 2) counterclash (ES, May/June 2002, July/August 2002, Sept/Oct 2002, Jan/Feb 2009, Sept/Oct 2010;CW 9/29/08, 12/13/10, 4/9/12, 4/21/14, 6/8/15, 4/23/18, 2/21/22, 12/19/22, 2/20/23)

Miscellaneous and unexplained forms of design transfer/duplication

Some presumed Canadian counterclashes may prove to be something else

 

Die deterioration/deformation errors

 

Exaggerated conventional die wear (CW 12/27/21, 2/5/24, 10/28/24)

Radial flow lines

Concentric flow lines (uncommon)

Parallel flow lines (promoted by pre-existing trails)

"Orange peel" effect

Design-devouring die wear (thinned letters and numbers) (CW 10/28/13, 2/22/16, 8/23/21)

Discrete lumps (CW 4/27/20)

Die deterioration doubling (CW 9/10/12)

Raised

Incuse (CW 2/4/08)

"Blebs" or "patches" (die erosion pits) (ES July/Aug 1998; CW 7/21/03)

Progressive indirect design transfer ("internal metal displacement phenomenon", "ghosting") (CW 6/7/10, 8/17/20)

Common in 1946-S and 1948-S cents

Surface-level die deformation errors (ES July/Aug 2001, Nov/Dec 2001) (CW 9/17/12)

(premature, localized, exaggerated, and peculiar patterns of deformation)

1943-S "goiter neck" quarter

Detail-erasing die deformation (2016-P Harper's Ferry quarter) (CW 2/27/17, CW 6/17/24)

"Ridge rings"

on copper-plated zinc cents (CW 2/14/05, 2/28/05)

on other U.S. denominations (CW 2/15/21)

on world coins (ES Sept/Oct 2006) (CW 2/17/14, 11/10/14)

Design berms (raised outlines) (CW 5/14/18, 11/6/23)

Die subsidence (sunken die) errors (ES July/August 2004, Nov/Dec 2004; CW 6/2/03, 11/29/04, 3/12/12, 2/12/18, 8/14/23)

e.g., 1924-S "goiter" cent

Co-occurring with split dies

Co-occurring with radial, antipodal die cracks (CW, 6/20/11)

1988-P nickels with lump on head (CW 4/4/11)

Massive die collapse in 2003-D dime (ES Nov/Dec 2011; CW 8/29/11)

Paralleling and flanking die cracks (CW 8/12/13)

Recurring die subsidence errors (CW 4/4/11, 3/31/14)

Linear die subsidence errors (CW 8/12/13)

Thermal warping (CW 5/29/23

Design creep

Reverse (hammer) 2014-P nickel die (CW 4/20/15)

In fractional Euro coins

Peripheral die expansion and erosion (CW 8/13/12, CW 4/13/15)

"Starburst" pattern of radial streaks (cause uncertain) (CW 8/15/05, 11/7/05)

Reciprocally deformed, convex-concave dies

Centrally-located deformation; 2001-P 50c) (ES Sept/Oct 2008; CW 1/19/15)

Peripherally-located deformation; India 2 rupees (CW 1/19/15)

 

Die breaks

 

Cuds (corner die breaks) (CW 10/17/11, 10/4/21)

Ovoid cuds

Irregular cuds

Crescentic cuds (ES March/April 2005; CW 2/15/16)

Circumferential cuds (ES March/April 2005; CW 2/15/16)

Elongate cuds (CW 12/8/14, 12/21/20, 7/31/23)

Rim-to-rim cuds (ES May/June 2003; CW 12/24/18)

On off-center or broadstruck coins (CW 9/12/11)

Deep vs. shallow die breaks (CW 6/2/20)

Retained Cuds (ES Jan/Feb 2006; CW 4/17/06, 7/24/06, 1/24/11)

Anvil die (diagnosis often in doubt)

Hammer die (doubtful) (CW 8/8/13)

With vertical displacement

With horizontal offset

With lateral spread

Outthrust (protrudes beyond die face) (CW 3/11/19)

Hammer die

Anvil die

Interior (internal) die breaks (ES May/June 2003; CW 10/25/10, 11/5/18, 8/14/23)

Connected to die cracks or splits

Freestanding (ES May/June 2005)

Retained interior die breaks (ES July/August 2004)

Connected to die crack or split die

Freestanding

Rim cuds (CW 5/3/21)

Die chips (CW 6/14/19, 7/8/19)

On raised die features (CW 2/28/22)

Catastrophic die failure (ES May/June 2007) (CW 5/20/13, 2/27/23, 6/19/23)

With associated collar damage (CW 6/17/19)

Spontaneous breaks

Breaks produced by impacts

Textured and dimpled cuds (CW 10/17/11,10/12/20)

Cryptic cuds (CW 4/17/23)

 

Die exfoliation errors (CW 10/19/20)

 

Collar breaks (collar cuds) (ES May/June 2008; CW 5/17/10, 11/22/10, 12/19/16)

Complete collar break (abrupt loss of entire arc segment) (CW 5/6/24)

Irregular collar break

Chipped collar

Vertical collar crack

Retained collar break

Rotating collar break (ES, July/August 2003; CW 1/6/03, 12/12/16, 4/20/20, 12/28/20)

Bilateral split collar

On off-center strikes (CW 9/9/19)

Catastrophic collar failure (CW 7/17/23)

Wandering collar scar (4/15/24)

 

Die cracks (CW 4/25/16)

 

Rim-to-rim

Arcing rim-to-rim ("pre-cud") (ES Jan/Feb 2006; CW 2/8/21)

With lateral spread

Blind-ended

Bi-level die cracks (ES July/August 2004)

Protruding marginal die segments (CW 5/19/14)

Radial, antipodal die cracks (with centralized subsidence) (ES Sept/Oct 2011; CW 6/20/2011)

Die crazing (crazed die) (CW 2/24/14)

Shattered dies (ES Jan/Feb 2006, May/June 2007; CW 4/7/08, 9/17/18, 4/6/20)

Two or more splits in die

Numerous wide, intersecting, raised die cracks

Numerous intersecting bi-level die cracks

Various combinations of brittle fracture

In response to impacts (CW 6/19/17)

Impact-induced die cracks (CW 6/19/17)

 

Split Dies (ES Jan/Feb 2006; CW 6/2/03, 4/10/06, 4/17/06, 6/20/2011, 5/11/15, 9/17/18, 4/26/21, 4/18/22, 7/18/22,)

 

Median (bisecting) split die

Asymmetrical split die (CW 7/31/23)

"False split" (radial, antipodal die cracks) (ES Sept/Oct 2011; CW, 6/20/2011)

 

 

Part V. Planchet Errors

 

Alloy errors

 

Improper alloy mix (CW 12/27/11, 1/30/23, 4/3/23)

Poorly mixed alloy

Incorrect proportions of metals

In conjunction with rolled-thick errors (1941 cents, mainly) (CW 10/15/12)

Gas bubbles (CW 11/19/12)

Intact ("occluded")

Ruptured

Slag inclusions (ES May/June 2006)

Intrinsic metallic inclusions (ES Sept/Oct 2006) (CW 12/27/11, 7/21/14)

Lamination errors

Loss before strike

Due to alloy contaminants (CWK 9/23/25)

Loss after strike

Lamination cracks

Retained laminations

Folded-over before strike (CW 10/22/12)

Internally split clad layer (CW 10/22/12, 6/26/17)

Split planchets

Before strike (CW 8/2/10)

After strike

Struck with another planchet on top or beneath

Split core (clad coins)

Clamshell split (CW 1/28/13)

Clamshell folded over before strike (CW 10/22/12, 1/28/13)

Hemi-split planchets (CW 10/9/23)

Copper-and-zinc composite "shells" (ES, May/June 2001)

Split-after-strike (N.B. these are probably all detached cap bottoms)

Cracked planchets (CW 9/28/15)

Broken planchets / coins (CW 3/14/11, 9/18/23)

Before strike

After strike

Brittle coins (cross-classified with annealing errors)

Radial planchet splits (when struck out-of-collar)

Delayed radial stress splits (CW 5/2/22)

Planchet cohesion errors (crumbling planchets) (CW 11/22/21)

Ragged clips (CW 2/29/16)

Ragged notch

Ragged perforations ("blowholes")

Fissures -- ragged and smooth

Stress-induced surface irregularities (CW 4/24/17)

 

Subsurface Corrosion (CW 12/21/15)

Plated coins

Copper-plated zinc cents

Solid coins

 

Rolling Mill Errors

 

Rolled-thick planchets

Rolled-thin planchets (CW 8/2/10, 7/16/18)

Tapered planchets (CW 12/20/10, 12/28/15)

On clad coins (clad layer absent) (CW 4/27/15)

Rolling indentations (ES Jan/Feb 2000; CW 2/7/11)

Rolled-in scrap (ES May/June 2006; CW 2/7/11)

Bristles from descaling brush (CW 3/10/03)

Roller marks (CW 10/13/14)

Rolled-in patterns and textures

Rolled-in cloth pattern (CW 3/21/16)

From damaged, defective, and deteriorating rollers (CW 2/14/22; CWK 10/16/25)

 

 

Blanking and Cutting Errors

 

Curved (concave) clips (CW 6/29/15)

Crescent curved clips

Bowtie clips (ES Nov/Dec 2005; CW 6/16/14)

Two large clips at opposite poles - ends rounded

Four clips - punch slices through strip with normal hole spacing

Struck chopped webbing

Straight clips (CW 1/14/13)

Smooth straight clips

Irregular straight clips

Sawtooth clips

"Incomplete straight clips" (actually struck-in cutting burrs)

Straight cutting burrs (CW 1/14/13, 5/16/16)

Corner clips ("outside corner clips") (CW 1/14/13)

Assay clips ("inside corner clip") (cross-classified with pre-strike damage) (CW 1/21/13, 6/12/17)

Ragged clips (also listed under alloy errors)

Incomplete punch (incomplete clip) (ES May/June 2005; CW 3/24/14)

Elliptical (convex) clips (ES May/June 2005; CW 4/5/10, 7/11/11, 8/5/24)

Multiple clips and combination clips (CW 1/27/14)

Blanking burrs ("rolling fold") (ES Jan/Feb 2007; CW 1/31/11, 5/29/17, 9/4/23)

Identically-positioned, same-source rolling folds (CWK 10/9/24)

Concave blanking burrs (CW 5/16/16)

Punched-in scrap (ES May/June 2006)

 

Upset Mill Errors

 

Coin struck on blank ("Type I planchet")

Abnormally weak upset (ES July/August 2005)

Abnormally strong upset (best seen on off-center strikes)

"Groovy edge" (possibly from worn groove in upset mill)

Variation in cross-sectional shape of rim/edge junction of planchet

Struck coin sent back through upset mill

Abnormal upset (ES Sept/Oct 2005; CW 2/27/12, 11/21/16)

Wide, flat edge

Smoothly convex edge

Abnormally wide proto-rim

Squeezed-in debris (upset mill inclusion) (ES May/June 2006; CW 9/6/2010)

Foil-like metal wraps around edge onto one or both faces

e.g. Copper foil on nickels (not from improper annealing)

Metal wire wraps around edge onto one or both faces

Pellet embedded in edge (CW 9/6/2010, 9/22/14)

 

Edge design errors (impressed into planchet before strike; includes security edge errors) (CW 6/27/16)

 

Edge design missing

Edge design present on normally plain edge (CW 6/27/16)

Wrong edge design

Edge design too high or too low

Interrupted edge design

Tilted edge design

Broken edging die (CW 6/27/16)

 

 

 

Mispunched center holes (foreign only) (CW 1/7/19)

 

Misaligned hole

Double-punched center hole (CW 5/27/24)

One hole centered

Both holes misaligned

Overlapping holes

Totally separate holes

Irregular center hole

Abnormally small hole

Partial hole (from broken hole punch)

Circular indentation (partial penetration)

Due to broken-off punch tip (rough surface)

Unpunched center hole

Hole punched in planchet meant for a solid coin

 

Annealing Errors

 

Improper annealing (due to excessive heat, prolonged exposure to intense heat, or excessive oxygen in annealing oven) (replaces "sintered plating" and "copper wash") (ES July/Aug 2010; CW 11/30/09, 2/8/10)

Black, brown, red, coppery discoloration (includes "black beauty" nickels)

Layer of copper, often peeling

Poorly annealed or non-annealed planchets (hard, brittle planchet) (CW 3/14/11)

Broken planchets and coins (CW 3/14/11, 9/18/23)

Radial cracks in coin (usually struck out-of-collar)

Brittle coins (cross-classified with alloy errors) (CW 3/14/11)

Abnormally hard planchets (CW 12/17/12, 8/15/22)

1954-S nickels

1983-P nickels (CW 4/11/11)

"Superclash" 2000-P nickel (CW 3/22/10)

On undersized or underweight planchets (CW 2/13/12)

 

Miscellaneous forms of mint discoloration

 

Plating Errors

 

Incomplete plating (CW 4/1/24)

Bulls-eye patterns of incomplete plating (CW 3/10/14, 10/27/14, 6/15/20, 8/12/24)

Unplated cents (CW 10/26/15, 7/24/23)

Cents struck on unplated or partly-plated foreign planchets (CW 3/10/14)

Thin plating

Thick plating (ES March/April 2009)

Blistered plating

Circular blisters

Linear blisters

Ruptured blisters

Brassy plating

Cracked, split, and peeling plating (CW 12/18/17)

 

Bonding/Bonding Mill Errors (ES Sept/Oct 2002)

 

Missing clad layer

Full

Before strike (CW 5/23/22)

After strike

Before rolling is completed (weight may be close to normal) (ES Sept/Oct 2002, Nov/Dec 2006; CW 5/28/12, 4/27/15)

Partial

Before strike

After strike

Before rolling is completed

Bifacial missing clad (12/2/24)

Thin cladding

With gaps

Missing both clad layers (struck core)

Core thickness (ES, Sept/Oct 2003) (CW 3/18/13, 2/3/20)

Full thickness

Struck clad layer

Separated after strike

Separated before strike

Struck by itself

Struck on top of or beneath a normal planchet

Clamshell separation (CW 1/28/13)

Clad layer folded over before strike

Missing core

Partial

Full (Coreless or all-clad coins) (CW 12/19/11, 7/29/24)

 

Irregular planchets

 

Scraps / fragments (CW 12/21/09, 1/27/20)

Normal alloy/composition

Off-metal

Feeder finger material

Foil

Heavier than normal coin of same denomination

Wider than normal coin of same denomination (along at least one axis)

Ragged clip (cross-classified with alloy errors)

Ragged notch (cross-classified with alloy errors)

"Blowhole" (cross-classified with alloy errors)

Fissure (cross-classified with alloy errors)

Cracked planchets (cross-classified with alloy errors)

 

Pristine planchets (i.e. lacking tumbling marks) (CW 1/11/16)

 

Pre-Strike Damage (CW 11/15/10, 1/23/12, 1/30/12, 12/15/14, 4/13/15, 6/8/20)

 

Assay clips (cross-classified with blanking errors)

Rim burrs (CW 1/31/11)

Accidentally and intentionally "resized" planchets (CW 9/15/10)

"Crimp marks" (mostly found on off-metal errors 5c/1c, 5c/10c)

Rockwell test mark in planchet (circular or oval dimple) (ES July/Aug 2006; CW 10/15/18)

Planchet with adjustment marks (gold or silver planchets filed to reduce weight)

Edge rolled, squeezed, and folded-over (or with thin apron produced) (CW 11/15/10; 1/23/12, 6/15/20)

Pre-plating damage (zinc cents) (CW 1/23/12)

Post-plating damage (zinc cents) (CW 11/15/10)

Scraped-in debris (CW 2/23/15; CWK 9/23/25)

Repetitive pre-strike damage (CW 12/15/14)

Other forms of pre-strike damage

Gouged (CW 1/14/19)

Crushed (CW 4/13/15)

Scraped (CW 2/23/15)

Torn

Crumpled (CW 8/15/11)

 

 

Inter-strike Damage (CW 1/9/12, 8/20/12)

 

Cancelled or defaced between strikes (CW 3/25/13)

 

Trans-strike damage (CW 7/12/21; CWK 5/27/25)

Wrong planchet and off-metal errors

 

Wrong planchet, correct composition

Off-metal

Domestic planchet (CW 6/22/20)

Foreign planchet

Unidentified origin and purpose (orphan) (ES Sept/Oct 2006, Nov/Dec 2006, March/April 2011, May/June 2011; CW 5/10/10, 12/19/11, 1/30/17, 11/30/20, 4/4/22)

Defective and damaged off-metal planchets (CW 3/21/16)

Foreign denomination struck on U.S. planchet

Pure copper quarters and dimes (covered under bonding mill errors)

Pure clad dime (covered under bonding mill errors)

Wrong stock errors (CW 2/20/12)

Correct composition

Off-metal (e.g, 1987-P nickel struck on clad quarter stock) (CW 4/22/13, 9/23/13, 9/10/18)

Transitional stock planchets (CW 9/23/13)

Business strike on special off-metal planchet (CW 2/10/20)

(e.g., 1974-D and 1977-D silver-clad Eisenhower dollar)

Special strike on business planchet (CW 2/10/20)

(e.g. 1973-S Eisenhower dollar on Cu-Ni clad planchet)

Business strike on proof planchet (CW 11/14/11)

Proof strike on business planchet

Wrong date error (covered under mules and die manufacturing errors)

Double denomination errors (CW 10/3/22)

Same year

Different year

Over pre-existing off-metal error (ES Sept/Oct 2017); CW 2/10/2014)

Dual country (CW 3/21/11)

Same year

Different year (CW 3/21/11)

Intentional overstrikes (not an error)

Transitional planchet errors ("wrong series") (ES Sept/Oct 2001; CW 3/28/16, 8/22/16)

Composition/year mismatch with non-overlapping production schedule

1943 bronze cents (CW 4/11/16)

Composition/year mismatach with overlapping production schedule

1965 silver dimes and quarters

1964 clad dimes and quarters

Intra-year design/composition mismatch

1991 Russia 10 kopek (ES Sept/Oct 2001)

Forward-jumping transitional planchet errors (CW March 20, 2017)

Transitional/wrong denomination error

(e.g. 1965 quarter struck on silver dime planchet)

"Long pause" transitional planchet errors (CW 4/5/21)

Struck on smaller planchet or coin

Struck on same size planchet or coin

Struck on re-sized planchet (dime design struck on cut-down cent planchet)

Struck on larger planchet or coin (CW 8/22/22; CWK 8/20/25)

1981 cent on nickel planchet, uniface reverse

1981 cent design on struck SBA dollar (several known)

1981 dime on cent cap

Canadian "assisted errors" 1977 - 1981

Struck on loose clad layer (covered under bonding mill errors)

Weld seam planchets (controversial) (CW 9/24/12)

Coin struck on washers, gears, and other hardware

Coin struck on aluminum feeder finger (CWK 12/3/25)

Experimental planchets (CW 11/23/15, 5/23/16)

Experimental wartime planchets (CW 12/7/09, 12/21/09)

1999 and 2000 state quarters on experimental planchets (CW 11/26/01)

1999 Susan B. Anthony dollars on experimental planchets (CW 8/5/02)

1974 and 1974-D aluminum and bronze-clad steel cents (CW 1/13/03)

 

Bi-metallic errors (foreign only) (ES Nov/Dec 2005)

 

Misaligned core (ES May/June 2007; CW 3/6/23)

Misaligned center hole (ES Sept/Oct 2007)

Well-seated core (CW 3/6/23)

With misaligned core (CW 3/6/23)

Double-punched center hole

Unpunched center hole

Solid disc of ring metal (CW 3/26/18)

Solid disc of ring metal with embedded core

Solid disc of ring metal with core indent

Ring with incomplete punch (ES Sep/Oct 2007)

Core with incomplete punch

Struck outer ring (ES Jan/Feb 2007)

Struck core (ES Nov/Dec 2006)

From another denomination

From another country (ES Sep/Oct 2009, Nov/Dec 2011)

Struck by solid-denomination dies

Wrong core inserted (ES Sep/Oct 2013, CW 10/17/22)

Core-sized scrap disc of ring material inserted into disc

Wrong ring (ES March/April 2007, CW 10/10/22)

Ring accidentally punched from solid planchet

Ring accidentally punched from solid coin (ES Nov/Dec 2008)

Struck ring from another country (restruck)

Struck core from another country (restruck)

Unstruck core inserted into struck ring and then restruck

Abnormally small core (controversial)

Abnormally wide center hole (controversial)

Abnormally thin core

Abnormally thick core

Abnormally thin ring

Abnormally thick ring

Incomplete trilaminar core

Missing one layer (ES Mar/Apr 2010)

Missing two layers

Core punched out of ring strip

Ring punched out of core strip

Bi-metallic planchet struck by solid-denomination dies

Solid-denomination planchet struck by bi-metallic dies (ES Mar/Apr 2014)

Bi-metallic planchet struck by wrong bi-metallic design

 

 

 

 

Part VI. Striking Errors

 

Unstruck blank ("Type I")

 

Unstruck planchet ("Type II")

 

Die alignment errors

 

Rotated die errors (CW 6/21/10, 7/9/12)

Rotated die due to improper installation (fixed rotation)

Rotated die due to improper die preparation (fixed rotation)

(e.g., grinding flats in wrong spot)

Rotated die due to movement after installation (dynamic rotation)

Semi-stable rotated die errors (various causes)

Characterized by a limited range of motion, a limited number of positions, or the presence of a single dominant position (CW 7/9/12, 8/7/23)

Perfect medal rotation (CW 9/16/24)

Pivoted die errors (probably involves entire die assembly) (CW 6/22/15, 10/21/19)

Horizontal misalignment (CW 10/27/03, 7/25/16)

Hammer die (CW 2/1/10, 6/25/12)

Anvil die (ES Sept/Oct 2004, March/April 2005; CW 9/27/10; 9/9/13, 1/19/15, 4/16/18, 1/4/21, 7/19/21, 12/9/24)

With misaligned collar

With broken collar

Dynamic misalignment (CW 6/25/12, 11/23/20)

Multiple misaligned strikes (CW 10/11/21, 11/29/21)

Stable misalignment

On double-struck coins

On first strike only (CW 8/31/20)

On second strike only (CW 5/19/08, 5/23/11, 9/9/13)

On both strikes

Alignment with off-center strikes (CW 8/19/19, 8/26/19)

Vertical misalignment (tilted die error) (ES Jan/Feb 2003, Sept/Oct 2003; CW 12/8/03, 12/20/10, 8/24/15, 10/24/16, 1/8/24)

Hammer die (CW 2/1/10, 6/17/13)

Anvil die

Dynamic misalignment (CW 10/24/16)

Stable misalignment (CW 1/29/14)

Associated with weak strike (2/1/10, 10/8/12, 8/16/21)

Associated with off-center strike (8/13/18)

Dual (bifacial) misalignments (dies often misaligned in different directions) (CW 11/28/11, 5/18/15, 1/9/17, 7/9/18, 8/26/19, 6/24/24)

Compound misalignments (CW 8/24/15)

Horizontal and vertical

Horizontal and rotated

Rotated and vertical (CW 12/20/10, 10/24/16, 5/25/20, 8/19/24

Horizontal, rotated, and vertical (CW 8/24/15)

Forced misalignments (CW 8/28/17)

 

Collar Alignment Errors

 

Misaligned collar

Associated with misaligned anvil die (CW 4/16/18)

Associated with stiff collar error

Associated with elliptical strike clip

Rotating collar (detectable only when there's a collar break and a multi-coin progression)

 

Collar deployment errors

 

Partial collar (CW 2/24/20)

Flange with bevel

Flange without bevel

Tilted partial collar

Undulating partial collar (CW 2/24/20, 7/25/22)

Re-entry partial collar

Incomplete ejection partial collar (CW 12/26/22)

Reversed partial collar (not an error)

Multiple steps (CW 3/15/21)

High deployment of collar with coin metal extruded beneath (doubtful)

Broadstrikes

Centered

Uncentered (CW 7/20/15)

Cupped broadstrike

Forced broadstrike (CW 1/10/11, 11/30/15)

Partial collar broadstrike (shows incomplete, tilted partial collar)

Stiff collar errors (ES, Nov/Dec 2000; CW 8/25/08, 4/16/18)

Normal die installation

Inverted die installation

Association with misaligned dies

Association with misaligned collar

Strong collar scar

Strong collar scar with cupping

Planchet forced completely into fully deployed collar ("ram strike") (ES Nov/Dec 2000, March/April 2001)

Elliptical strike clip (ES March/Apr 2000; CW 4/5/10)

Associated with weak strike (CW 2/11/13)

Collar shimmy (CW 8/21/17, 9/11/17)

 

Weak Strikes (ES, Sept/Oct 2000; CW 5/3/04, 9/11/06, 6/18/07, 3/1/10, 5/23/11, 6/23/14, 8/27/18, 3/2/20, 10/26/20, 11/27/23; CWK 8/25/25)

 

Caused by insufficient die approximation

Caused by abnormally low ram pressure

Invisible strikes (ES March/April 2003, Nov/Dec 2003, March/April 2004, Nov/Dec 2006, May/June 2010; CW 5/3/10, 9/20/10)

With indent

With partial brockage

With struck-through error

Followed/preceded by strong strike (CW 7/13/20)

Stable series of weak strikes (CW 8/27/18)

Weak saddle strike

One strike weak, one strong (CW 4/8/13)

Both strikes weak (CW 12/12/11)

In combination with other striking errors

Rim-restricted first strike (CW 3/1/10, 10/10/11, 1/11/16, 2/19/18, 9/23/19)

Rim-restricted second strike (CW 9/21/15, 2/13/17)

 

Skidding Coin Errors (CW 1/29/18)

 

Finned Rims (CW 7/6/20)

 

Caused by elevated ram pressure

Due to multiple strikes combined with reduced minimum die clearance (CW 12/7/20)

Due to stacked coin metal discs

 

Abnormally Strong Strikes

 

Due to elevated ram pressure

Finning (CW 8/23/04, 7/6/20)

Extremely large broadstrike (CW 7/26/10)

Extreme stretch strikes with both sides die-struck

Encircling pressure bumps (CW 12/2/23, 5/13/24)

Due to stacked coins or planchets (CW 12/7/20)

Localized, due to die tilt

 

Stutter Strikes (ES Nov/Dec 2001, Sept/Oct 2007; CW 12/28/09, 7/25/11, 8/10/20)

 

Due to spasmodically collapsing or stiff collar (Type I)

Due to planchet flexion (associated with indents and brockages) (Type II)

Due to contact with bent planchet or coin (Type III)

On face struck by anvil die (CW 8/26/13)

 

Concentric strike lines generated by a single strike (ES Jan/Feb 2012; CW 12/26/11)

 

Machine doubling (a.k.a. machine doubling, machine doubling damage, machine damage doubling, mechanical doubling, strike doubling, shift doubling, "ejection doubling") (ES July/Aug 2006; CW 3/15/10, 7/24/17, 12/23/19, 3/30/20)

"Push doubling" (marginal shelving and sharp interior duplication) (CW 1/9/23)

"Slide doubling" (smeared design) (CW 8/14/17)

Compensatory, retrograde machine doubling (CW 4/29/24)

Rotational machine doubling (CW 8/10/15)

Intermediate forms

Multiple machine doubling in one direction (two, three, and four offset ranks)

Machine doubling in more than one direction (up to three directions)

Machine doubling on both faces of same coin (CW 3/15/10, 12/23/19)

Rim-restricted design duplication (see separate category)

Affecting incuse design elements (CW 2/6/06, 1/16/12)

Located on top of die break

Located on top of die attrition error (CW 4/14/14)

On out-of-collar strikes (rare) (CW 11/25/19, 11/21/22)

 

Rim-restricted design duplication (form of machine doubling) (CW 10/6/03, 2/22/10, 5/24/10, 12/6/10, 5/13/13, 12/30/13, 3/8/21, 4/12/21)

 

2004 cent (ES March/April 2007; CW 2/22/10)

1994 cents (CW 5/24/2010, 8/22/2011)

1981-P quarter and 1979-D dime (CW 12/30/13)

Presidential dollars (ES, Sept/Oct 2007) (CW 2/22/10, 12/6/10)

Foreign coins (CW 2/22/10)

On face struck by anvil die (CW 10/21/13, 7/20/20)

Bifacial (CW 7/20/20)

In conjunction with push doubling (CW 12/6/10, 7/20/20)

 

Ejection Doubling (CW 11/7/22)

 

Skidding Die Errors (CW 8/15/16, 11/27/17)

 

Design ablation error (design scraped off by die movement on 2^nd strike) (ES March/April 2008, Jan/Feb 2011; CW 9/13/10)

Skidding misalignment (CW 8/15/16)

Two-stage (CW 4/13/20)

Design Decapitation Error (top of design scraped off)

Slide doubling (see Machine Doubling)

Combined with tilted die (CW 9/27/21)

From broken die (CW 7/26/21)

 

One-sided double-strikes (ES March/April 2000, Jan/Feb 2002, July/August 2003)

 

Hammer die rotated (CW 11/29/10)

Instantaneous

Gradual

Hammer die misaligned (CW, 5/19/08, 5/23/11, 9/9/13, 3/8/21, 4/24/23)

Instantaneous

Gradual

Anvil die misaligned (CW 9/9/13, 8/31/20)

Anvil die rotated (at least one known example, a proof Kennedy half dollar)

Rotated, with rocking die (CW 5/25/20)

False one-sided double strikes (CW 11/29/10)

 

Flat Field Doubling (Imperfectly Aligned Proof Strikes) (CW 4/29/13)

 

Off-center strikes

 

Cupped off-center strikes

With collar scar

Without collar scar

Uniface strikes

Stretch strikes

Uniface

Die struck on both faces (covered under high pressure strikes)

With unexplained, flat dent at opposite pole

(not a "sideneck strike")

 

Chain strikes (CW 4/12/10)

 

Normal chain strikes with straight edge

External chain strikes (ES Jan/Feb 2003)

Concave, convex, sinuous, and irregular chain strikes (ES Jan/Feb 2001, July/August 2002; CW 4/12/10)

 

Foreign Object Chain Strikes (CW 5/25/15)

 

Chain strike against feeder

 

Machine Part Impingement (CW 5/25/15)

 

Bilateral (CW 11/25/24, CWK 12/3/25)

Unilateral

 

Saddle (Tandem) Strikes (CW 6/27/11)

 

Hump present

Hump absent

Inverted hump (hump points toward reverse die) (CW 9/19/16)

Buckling toward anvil die

Due to inverted die setup

One off-center strike underthrust (CW 9/2/24)

Die position

Head-to-head

Head-to-base (early to mid- '70s, mainly)

Face-to-back

Other orientations

Gap between adjacent dies

Narrow

Wide

With inverted die installation

Sideneck strikes ("one-die saddles") (Expanding planchet collides with side of die neck) (CW 5/30/11)

On quarter dollars (CW 12/9/19)

Broadstrikes (covered under collar deployment errors)

 

Split Plating Doubling

 

Foldover Strikes (ES July/August 2007; CW 10/10/05, 8/15/11, 1/30/12, 9/15/14)

 

Out-of-collar

In-collar

With edge strike persisting

On struck cents (normal and error)

Double foldover strikes ("Z-fold")

Axial fold

Paraxial fold

Inward fold

Outward fold

 

Edge Strikes (CW 7/18/11, 10/12/15, 3/1/21)

 

Flat

Bent

With off-center strike or broadstrike produced by continuation of downstroke

 

Extrusion strikes (an effect, not an independent error) (ES March/April 2004; CW 10/24/11, 1/15/18)

 

With indent or partial brockage

Between two indents or partial brockages

With struck-through error

Struck through clipped planchet

With retained cud

 

Multiple strikes (CW 3/30/15)

 

On-center/Off-center

In-collar/out-of-collar

Flipover

Numerous closely-spaced strikes (ES Nov/Dec 2004; CW 1/11/21)

Involving second die pair

Delayed second strikes (ES July/August 2007; CW 1/9/12, 6/13/16, 6/6/22, 1/23/23)

Dual-date double strikes (CW 6/13/16)

Proof double strikes (CW 9/19/22)

 

Coins thinned by strikes

 

Die-struck on both faces

Uniface (CW 12/7/20)

In-collar (CW 6/3/19, 12/7/20

Out-of-collar

 

Indents

 

In-collar/out-of-collar

Partial

Full (CW 7/30/12)

Centered

Uncentered

"Internal" indents (CW 11/1/10, 2/8/16)

On obverse

On reverse

Multiple indents

Irregular indents

Produced by error coins

Produced by clipped planchet

Unexpectedly shallow indents (CW 12/28/20)

Indent by smaller planchet (CW 5/19/08)

External disc impressions (CW 3/18/2019)

 

Brockages

 

Full

              Centered

              Uncentered

Rotated (relative to die-struck design on opposite face)

Partial

Conventional

Aligned partial brockage (ES, May/June 2005; CW 1/17/11, 12/5/22)

                    From partial die cap

                    From elliptical clip coin

                    From elliptical strike clip

Internal partial brockage (CW 11/1/10)

In-collar/out-of-collar

From another denomination (ES May/June 2005, CW 8/1/21)

From another error coin

From wrong planchet error (CW 11/28/22, 6/12/23; CWK 8/4/25)

From mangled and crumpled coins (often multi-struck) (CW 10/2/23)

From weakly-struck coins (CW 11/20/23)

From die caps derived from error coins (CW 10/7/24)

Flipover brockage (CW 4/23/12)

On obverse

On reverse

First-strike brockage

"Mirror" brockage (unexpanded, undistorted) (CW 6/13/11, 3/17/14, 5/6/19, 10/28/19, 7/11/22, 6/27/22, 4/10/23)

Distorted first-strike brockages

Mid-stage and late-stage brockages

By struck fragment (CW 6/11/12)

Aligned with opposite, die-struck design

Not aligned with opposite design

From thin pieces of metal (CW7/23/18)

From struck die fill (very rare) (CW 8/20/18)

From large dropped filling (CW 5/13/19)

Multiple brockages (CW 9/26/11)

From multiple strikes

From clashed cap

From multi-struck coin (CW 7/4/22)

From more than one coin in striking chamber

From coin trapped between die cap and planchet

Clashed cap strikes (CW 8/30/10, 11/21/11, 1/13/14)

From a late-stage die cap that clashed with the opposite die

From a uniface die cap that clashed with the opposite die

From an early-stage die cap that clashed with the opposite die

From a cap that was striking counterbrockages that clashed with the opposite die

From a flipover die cap that clashed with the opposite die (CW 1/13/14)

 

Counterbrockages

 

Full (CW 10/11/10)

Partial (CW 11/8/10)

In-collar/out-of-collar

Counterbrockage of obverse on obverse

Counterbrockage of reverse on reverse

Flipover counterbrockage (CW 4/19/21)

Early, middle, and late-stage counterbrockages

From another error coin

Brockage-counterbrockage combination (8 types) (ES, Nov/Dec 2009) (CW 11/12/12)

Multiple counterbrockages (ES March/April 2010)

On second strike

Rebound counterbrockage (always on 3^rd strike) (CW 11/9/15, 3/4/2024)

Secondary counterbrockage (CW 4/19/21, 9/23/24)

Grease-generated counterbrockage (CW 4/11/22)

 

Horizontal lipping (CW 11/30/15)

 

In conjunction with indents, partial brockages, and struck-through errors

 

Die caps (CW 8/6/13, 1/7/20)

 

Hammer die caps (usually the obverse die)

Raised design on working face

Brockage on working face

Uniface die caps

Complex die caps

Anvil die caps (usually the reverse die)

Cupped toward anvil die, hammer die, both dies at opposite poles, or expanded in the horizontal plane

Partial (off-center) die caps (hammer or anvil) (CW 1/17/11)

With cupping

Without cupping

Detached cap bottoms (ES March/April 2001, May/June 2001)

Clashed caps (CW 1/22/24)

Die caps derived from error coins (CW 10/7/24)

 

Capped die strikes (generic -- without identifiable images)

 

Struck by uniface die cap

Struck through late-stage die cap

Struck through cap-like obstruction

Struck through split or torn cap

Proportional design expansion (both faces struck through die cap or cap-like obstruction) (CW 11/11/13, 5/28/18)

 

Struck by impaled die cap (CW 6/10/13)

 

Capped die doubling (doubling associated with capped die strikes) (ES Sept/Oct 2005; CW 6/18/12, 5/16/22)

 

Shifted/rotated cap strikes (ES May/June 2000, March/April 2012; CW 11/21/11)

Correctly-facing incuse design elements (CW 11/3/08, 6/28/10, 6/11/12, 10/19/15, 8/12/19, 10/23/23, 11/13/23)

Multiple sets due to several preceding shift-and strike events

Unexplained, close raised doubling

Expansion ripples

Other forms of close raised doubling

Incuse doubling surrounding raised elements (CW 8/24/20)

 

"Struck-through" errors

 

Struck through fragment

Struck through die fragment (CW 7/15/24)

Struck through fine particles (CW 6/10/24)

Struck through clipped planchet (ES Sept/Oct 2002; CW 8/25/14, 6/3/24)

Struck through thin struck fragment (CW 6/11/12, 10/19/15, 8/12/19, 10/23/23, 11/14/23, 8/26/24)

Face-up (correctly-facing incuse design elements)

Face-down (mirror-image design elements)

Trapped between planchet and opposite die (mirror-image design elements)

Struck through detached lamination flake (CW 2/7/05, 6/11/12)

Struck through clad layer

Clad layer unstruck

Clad layer previously struck

Struck through reeding (CW 11/14/16, 8/21/23)

Struck through split planchet

Obverse

Reverse

Struck through hardware (bolts, screws, washers, etc.) (CW 3/7/11)

Struck through chain (CW 4/22/24)

Struck through feeder (ES Nov/Dec 2005; CW 3/7/11, 12//25/23)

Struck-through unidentified machine part (CW 6/24/13)

Struck through emery disc (CW 12/16/02)

1986 Silver Eagles

Struck through "grease" (die fill)

Assorted ingredients, textures, viscosities, and consistencies (smooth, coarse, stiff, viscous, etc.)

"Greasy ghosts" (ghost images from grease accumulations) (CW 7/5/10, 7/10/17)

Grease-mold doubling (ES March/April 2006, July/August 2006, Nov/Dec 2008; CW 8/19/13, 10/20/14, 10/14/24)

Grease-mediated radial smear (CW 7/31/17)

"Spackled dies" (intentionally applied grease) (CW 10/18/21)

Bifacial grease strikes (5/22/23)

Filled dies

Single design element (CW 6/29/20)

Multiple design elements

Struck through bulging die filling (CW 1/16/17, 5/20/19)

Filled collar /obstructed collar (ES Jan/Feb 2006; CW 9/22/14)

With flange

Surface film effects (ES May/June 2002; CW 9/1/08)

Surface film doubling

Surface film afterimage

Surface film transfer

Surface film transfer with clash marks

Dropped fillings (ES May/June 2003; CW 8/16/10, 6/11/12; 10/29/12)

Isolated elements (dropped letter, dropped number" (CW 2/7/05)

Conjoined dropped fillings (CW 8/16/10)

Large, multi-element dropped fillings (CW 4/19/10, 8/16/10, 11/14/22)

Retained dropped fillings

Yanked-out fillings (CW 1/16/23)

Struck through floating encrustation (on second strike) (CW 1/18/16, 6/18/18)

Struck through miscellaneous foreign matter

Metal dust, shavings

Thread, string (CW 3/9/20)

Cloth (CW 5/14/12, 12/3/18, 9/26/22)

String (CW 3/9/20)

Wire (CW 5/20/24)

Struck-through on edge (CW 5/20/24)

Feeder-applied struck-through errors (CW 11/18/13, 4/8/24)

Split or torn in two by struck-thru object (ES Nov/Dec 2007; CW 3/7/11, 7/13/15. 3/11/24, 7/1/24)

Retained struck-through errors (struck-in errors) (CW 7/18/16, 1/25/21, 9/13/21)

Embedded dropped filling (see above)

Embedded die fill (shapeless)

Scrap metal

"Staple" (bristle from wire brush)

Plastic (associated with bullion coins)

Metal foil

Cu-Ni?; associated with dimes and nickels

Copper foil (ES Nov/Dec 2007)

Rubbery material (from die cover?)

Die fragment (CW 2/6/23, 3/13/23)

 

Uniface strikes (cross-classified with Indents) (CW 7/30/12, 9/16/19)

 

In-collar (CW 12/5/22)

On second strike (CW 11/29/10, 9/16/19, 6/5/23)

"Augmented" in-collar uniface strikes (CW 9/14/20)

Out-of-collar

Centered

Off-center

Sandwich strike (coin struck between two coins or planchets) (CW 5/16/11, 10/31/16, 11/20/17, 5/28/18, 3/22/21, 11/4/24)

 

Partial

Full

Between two struck coins

Between two planchets

Between a coin and a planchet

Between struck coin and obverse die cap

Between obverse and reverse die cap

 

Nested coins (CW 3/16/20, 11/18/24)

 

Mated pairs (CW 11/9/20)

 

Bonded coins

Pile-ups, clusters

Strike clips (ES July/Aug 1999, May/June 2001; CW 6/15/15)

 

Vertical shear clips (V)

Sheared between die and collar alone

Sheared between collar and overlying planchet

Horizontal shear clips (H)

Tensile strike clips (T)

Concave strike clips (V, H, T)

Elliptical strike clips (V, H, T) (CW 4/5/10, 12/5/22)

Straight strike clips (H)

Saddle strike/strike clips (H)

 

Detached reeding

 

From forced broadstrikes

From stiff collar

Torn-off fin

 

Coin shrapnel ("breakaway fragments")

 

Angular

Crescentic

Oval

Circular or sub-circular

Semilunar

Irregular

 

Intra-Strike Damage (Damage coincident with strike) (CW 5/30/2011, 12/20/21)

 

Flat contact facet at 6:00 opposite off-center strike

Machine part impingement on unstruck portion of off-center coin (CW 5/25/15)

Ejection damage to edge of unstruck perimeter

External struck-through errors (with cupping) (CW 3/25/19)

Concave damage opposite off-center strike (CW 12/30/19)

 

Cupping (CW 12/7/09)

 

With and without collar scar

In a single strike

Associated with multiple strikes

With die caps

Cupping toward hammer die

Cupping toward anvil die

Expansion in horizontal plane

On unobstructed strikes (CW 3/18/19)

Spontaneous

Forced

By stiff collar

By outlying disc of coin metal

By foreign object or machine part

 

Impact-Induced Warping (CW 3/16/15, 1/13/20)

 

Crenellated rim (generated during ejection) (CW 10/23/17)

 

Malrotation Errors (multi-sided coins only) (CW 3/23/15, 11/8/21)

 

Proof edge lettering errors (generated during strike by segmental collar)

Weak edge design due to segmented collar not closing fully (wide seams)

Segments arranged in incorrect sequence (see Die Installation Errors) (CW 4/7/08)

 

 

 

Part VII. Post-Strike Mint Modifications

 

Edge lettering applied after strike (incuse) (Business strike Presidential dollars, Native American dollars, and final Sacagawea dollars)

 

Absent lettering (CW 4/26/10)

Due to bypassing the lettering device

Due to excessive spacing between steel wheel and lettering die

Vertically misaligned letters (cut off at top)

Vertically misaligned letters (cut off at bottom)

Wrong spacing between incuse design elements

Obliquely-oriented lettering

Overlapping letters

Two sets of letters

Skipped letters

Letters on wrong planchet

2007-D Sacagawea dollar with Presidential edge lettering (CW 7/9/12)

Chipped letter

Lightly impressed letters (CW 4/26/10)

Unusually deep letters (Coin squeezed too hard, leaving a rippled margin)

Incomplete letters

Smeared letters

Edge letter font subtypes (CW 10/18/10)

Wrong date on edge (doesn't match any President of that year) (CW 2/22/10, 3/1/10)

2009 Zachary Taylor dollar with 2010-D edge inscription (CW 2/22/10, 3/1/10)

Edge lettering on unstruck planchet (CW 3/26/07, 3/17/08)

Lettering die inclusion (CW 9/14/15)

 

Note: Edge lettering and other edge design elements may be impressed during upsetting, during the strike, by a special machine before the strike, or by a lettering device after the strike. Similar-looking defects can occur in each of these processes. Any edge design that forms a closed interlock between the edge of the coin and the collar cannot be produced during the strike since that will prevent ejection of the coin after the strike.

 

Post-strike chemical treatment

 

Anti-tarnishing Experimental Rinse on Sacagawea dollars

 

Matte or frosted finish applied after strike

 

Finish omitted on one or both faces (CW 8/1/11, 8/29/11)

Part VIII. Post-Strike Striking Chamber Mishaps

 

Post-strike die contact

 

Ejection impact doubling (post-strike design transfer from die) (ES Jan/Feb 2005; CW 8/1/05, 8/29/05, 2/25/13, 2/26/2018, 4/9/18, 10/8/18, 4/12/21)

 

Ejection damage

 

Crenellated rim (CW 10/23/17)

Feeder/ejector scrapes on coin (CW 3/19/18. 3/7/22)

 

 

Part IX. Post-Strike Mint Damage

 

Illicitly applied die impressions (CW 11/16/20, 1/4/21, 2/1/21, 8/29/22)

 

Pseudobrockage (false brockage) (ES Nov/Dec 1999) (CW 8/23/10)

 

Fused coins

 

Rolled and squeezed

 

Accidentally resized

 

Other (folded, crushed, scraped, bent, etc.)

 

 

Part X. Wastebasket/Composite Categories

 

Ghost images (CW 8/1/11)

 

Progressive indirect design transfer (a.k.a. internal metal displacement phenomenon, ghosting, heavy design transfer) (CW 6/7/10)

Worn clash marks

Thin planchet (CW 8/2/10)

Split planchet (CW 8/31/15)

Split-before-strike (CW 8/2/10)

Split after-strike

Coin thinned by strike(s) (CW 6/3/19, 7/8/24)

Weak strike (CW 4/11/2011)

High pressure strike

"Greasy ghost" (CW 7/5/10)

Surface film afterimage (CW 5/2/11)

Surface film transfer (CW 5/2/11)

Split plating afterimage (CW 5/2/11)

Coarsened crystallite afterimage (CW 5/2/11)

Slide zone ghost letters (11/16/15)

Incuse ghost images associated with capped die strikes (CW 10/25/21)

 

Doubling

 

Die Deterioration Doubling

Raised

Incuse

Machine Doubling

Stutter strikes (3 types)

"Abrasion doubling" (extremely doubtful) (CW 7/15/13)

Split plating doubling) (CW 3/26/12)

Surface film doubling

Grease-mold Doubling (CW 8/19/13)

Longacre doubling

Offset laser-etched frosting on proof dies (CW 2/21/2011)

Plating disturbance doubling (CW 3/28/2011)

Flat-field doubling (imperfectly aligned proof strikes (CW 4/29/13)

Embedded matter (CW 12/14/09)

Poured-in

Slag

Intrinsic metallic inclusion

Rolled-in

Punched-in (by blanking die)

Squeezed-in (upset mill inclusion) (CW 9/6/10)

Scraped-in (CW 2/23/15)

Struck-in

Lettering die inclusion (CW 9/14/15)

 

Edge overhangs (CW 11/30/2015)

 

Partial collar errors

Horizontal lipping

Stiff collar errors

Forced broadstrikes