Part VI. Striking Errors:

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)
- Pivoted die errors (probably involves entire die assembly) (CW 6/22/15)
- 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, 1/19/15, 1/4/21, 7/19/21)
    - With misaligned collar
    - With broken collar
  - Dynamic misalignment (CW 6/25/12)
  - 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 misalignments (both dies misaligned in different directions) (CW 11/28/11, 5/18/15, 1/9/17, 7/9/18)
- Compound misalignments (CW 8/24/15)
  - Horizontal and vertical
  - Horizontal and rotated
  - Rotated and vertical
- Forced misalignments (CW 8/28/17)

Collar alignment errors

- Misaligned collar
  - Associated with misaligned anvil die
  - 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)
  - 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)

- 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)

Abnormally Strong Strikes

- Due to elevated ram pressure
  - Finning (CW 8/23/04, 7/6/20)
  - Encircling pressure bumps (CW 12/2/23)
- Due to elevated ram pressure or reduced minimum die clearance
  - Extremely large broadstrike (CW 7/26/10)
  - Extreme stretch strikes with both sides die-struck
- 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)
- 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 5/24/10, 8/22/11)
- 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 (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)

- Skidding misalignment
  - Two-stage (CW 4/13/20)
- Design decapitation error (top of design scraped off)
- Slide doubling (see Machine Doubling)
- Design ablation error (design scraped off by die movement on 2^nd strike) (ES March/April 2008, Jan/Feb 2011; CW 9/13/10)
- 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)
- 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 Strike (CW 5/25/15)

- Chain strike against feeder

Machine Part Impingement (CW 5/25/15)

- Bilateral
- 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
- Die position
  - Head-to-head
  - Head-to-base (early to mid- ’70s, mainly)
  - Face-to-back
- 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)

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 strike (ES July/August 2007; CW 1/9/12, 6/13/16, 6/6/22, 1/23/23)
- Dual-date double strike (CW 6/13/16)
- Proof double strikes (CW 9/19/22)

Indents

- In-collar/out-of-collar
- Partial
- Full (CW 7/30/12)
  - Centered
  - Uncentered
- “Internal” indents (CW 11/1/10, 2/28/16)
  - On obverse
  - On reverse
- Multiple indents
- Irregular indents
  - Produced by error coins
  - Produced by clipped planchet
- Indent by smaller planchet (CW 5/19/08)
- External disc impressions (CW 3/18/19)
- Unexpectedly shallow indents (CW 12/28/20)

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)
  - From mangled and crumpled coins (often multi-struck) (CW 10/2/23)
  - From weakly-struck coins (CW 11/20/23)
- 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 struck die fill (very rare) (CW 8/20/18)
- From thin pieces of metal (CW 7/23/18)
- 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)
- Secondary counterbrockage (CW 4/19/21)
- Grease-generated counterbrockage (CW 4/11/22)

Horizontal lipping (CW 11/30/15)

- In conjunction with in-collar 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)

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 de-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 event
- Unexplained, close raised doubling
  - Expansion ripples
- Incuse doubling surrounding raised elements (CW 8/24/20)

“Struck-through” errors

- Struck through fragment
- Struck through clipped planchet (ES Sept/Oct 2002; CW 8/25/14)
- Struck through thin struck fragment (CW 6/11/12)
  - Face-up (normally-oriented 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 feeder (ES Nov/Dec 2005; CW 3/7/11)
- Struck-through unidentified machine part (CW 3/7/11)
- Struck through emery disc (CW 12/16/02)
  - 1986 Silver Eagles struck through emery disc (CW 12/16/02)
- 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)
  - Grease-mediated radial smear (CW 7/31/17)
  - “Spackled dies” (intentionally applied grease) (CW 10/18/21)
  - Bifacial (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 2003; CW 8/16/10, 6/11/12, 10/29/12)
  - 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
- Struck through floating encrustation (on second strike) (CW 1/18/16, 6/18/18)
- Yanked-out fillings (CW 1/16/23)
- Struck through miscellaneous foreign matter
  - Metal dust, shavings
  - Cloth (CW 5/14/12, 12/3/18, 9/26/22)
  - String (CW 3/9/20)
  - Wire
- Field-restricted struck-through errors (CW 11/18/13)
- Split or torn in two by struck-thru object (ES Nov/Dec 2007; CW 3/7/11, 7/13/15)
- 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)
  - Die fragment (CW 2/6/23, 3/13/23)
  - 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?)

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)

- 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)

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 5/30/11, 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 (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 metal or machine part

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

Malrotation Errors (multi-sides 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 VI. Striking Errors:

Green lettering – major heading

Blue lettering – linked to subject matter

Brown lettering – subject matter covered under that heading

Black lettering – no entry yet