|
|
The 1970 Philippines 25 sentimos shown above wass normally struck on a 70% copper, 18% zinc and 12% nickel planchet that weighed 4.0 grams. However, this coin was struck on a 3.1 gram, United States 1 cent planchet. This may have been an assisted or intentional error, but this must be weighed against the fact that the United States Mint was striking this coin type for the Philippine government at the Denver mint in 1970. This coin has been authenticated by NGC and is in the collection of Jim Zimmerman. |
Struck Through String
Part VI. Striking Errors:
“Struck-Through” Errors:
Struck Through Miscellaneous Foreign Matter:
Struck through string
Definition: A coin struck through cordage, string, thread, or some other twisted or multi-filament fiber.
The nature and origin of such “strings” is often unclear. The width, coarseness, stiffness, complexity, and composition of these strings is highly variable. However, it’s clear that some strings represent cloth that has unraveled. In some instances, the edge of a struck-through-cloth error will degenerate into a field of strings.
This 1955-D cent was struck through one or more convoluted strings that likely represent an unraveling patch of cloth.
This 1976 features a partial struck-through-cloth error. The left margin of the cloth impression shows signs of unraveling.
External Struck-Through Errors (With Cupping)
Part VI. Striking Errors:
Intra-Strike Damage:
External Struck-Through Errors (With Cupping)
Cross-referenced as:
Part VI. Striking Errors:
Cupping:
On Unobstructed Strikes:
Forced:
By Foreign Object or Machine Part
Definition: The unstruck portion of an off-center planchet is forced down upon an underlying obstruction by the impact of the hammer die. This forces the unstruck portion of the coin upward and simultaneously leaves the underside of the unstruck crescent with an indentation which is called an external struck-through error.
This 2000-D Virginia quarter was struck off-center. The portion of the planchet that protruded outside the striking chamber rested on an obstruction. The impact of the hammer (reverse) die caused the presumed foreign object or machine part to push the unstruck crescent into a vertical orientation. It also generated a short arc of design rim. The external struck through error can be seen on the outside of the cupped portion of the unstruck crescent.
This off-center 2003 India 5 rupee coin features an external struck-through error and forced cupping generating by the foreign object or machine part that was positioned beneath the unstruck portion of the coin. The unstruck crescent is tilted upward at an angle of around 45 degrees. An arc of design rim formed along the base of the internal surface of the inclined metal.
Struck Over Pre-Existing Wrong Planchet/Off-Metal Error
Part V. Planchet Errors:
Wrong Planchet and Off-Metal Errors:
Double Denomination Errors:
Struck Over Pre-Existing Wrong Planchet/Off-Metal Error
Definition: A design struck over another design (either domestic or foreign) which was, in turn, struck on the wrong planchet. Such errors are quite rare, with a significant proportion intentionally fabricated inside the mint.
This state quarter design was struck over a 2000-P nickel design which had been, in turn, struck twice on a cent planchet. The quarter strike was off-center and has a first-strike brockage of the obverse quarter design on its reverse face. This error may have had some assistance in its creation. Photos courtesy of Terry Holcomb.
This 2004 Canadian cent design was struck over a 2004 Papua New Guinea 1 tohea design which had itself been struck on a Fiji one cent planchet. The coin was cherrypicked from eBay by James Zimmerman, who expended a great deal of time and effort in identifying the host coin design and the original purpose of the planchet. This seems to be a truly accidental error. Photos courtesy of James Zimmerman.
This 1983 Canadian cent design was struck on an Israel 10 shekels design which was originally struck on a Canadian 1 cent planchet. As such, the final strike generated a dual country / double-denomination error but not a wrong planchet error. This is almost certainly an intentional error because it was struck in-collar. The original off-metal coin would have to have been resized after the first strike, which would have caused the coin to expand beyond the diameter of the collar. Photos courtesy of Fred Weinberg.
This 1982 Costa Rica 25 centavos design was struck over an Israel 10 shekels design which had originally been struck on a Costa Rica 25 centavos planchet. As with the previous coin, the final strike generated a dual country/double denomination error but not a wrong planchet error. And as with the previous coin, the last strike was in-collar, which would have required resizing of the expanded off-metal 10 shekels. Photos by Mike Diamond
Field-restricted struck-through errors
Part VI. Striking Errors:
“Struck-Through” Errors:
Field-Restricted Struck-Through Errors
Definition: Foreign matter that is exclusively or largely restricted to the field portion of the die face. The foreign matter is a gritty paste that is spread onto the die face by a feeder that is coated with the substance. The resulting pits and channels that appear on the face of the coin show a consistent directionality mirroring the movement of the feeder. The pits and channels may be surrounded by a shallower, more diffuse area (the smooth portion of the chunky peanut butter-like substance). The pits and channels may co-occur with die scrapes traveling in the same direction. These are also caused by the feeder.
As one would expect, field restricted struck-through errors are more common on the face struck by the anvil die. But they can occur on the face struck by the hammer die or on both faces simultaneously.
This 2007 cent shows a field-restricted struck-through error on the obverse face, which was struck by the anvil die. The northwest to southeast orientation of the pits and channels is typical and consistent from die to die.
This 2008 cent has a virtually identical field-restricted struck-through error.
Struck Through Floating Encrustation
Part IV. Striking Errors:
Struck-Through Errors:
Struck Through Floating Encrustation
Definition: A floating encrustation is a piece of compacted die fill or caked-on grime that enters the striking chamber and is struck into a coin. Stiff, caked-on grime can come from the bowels of the press. The lubricated joints and rods are a magnet for dust and dirt. This material can stiffen over time and then break off. Die fill (“grease”) is a compacted layer composed of lubricant, dirt, and metal dust that accumulates on the die face. Pieces can break away to form nondescript struck-through errors. In either case, the resulting struck-through error resembles a conventional “grease strike”.
The impression left behind by a floating encrustation can be expected to show:
- Soft or indistinct margins
- Variable depth (reflecting variable thickness of the foreign material)
- Variable topography (potentially smooth to rough)
- Occasional gaps or thin areas that allow the design to emerge.
There are only two practical ways to distinguish a floating encrustation impression from a grease strike:
- Assemble a progression (defined by die markers) that shows the sudden appearance of a struck-through area.
- Find a double-struck coin in which the first strike is unobstructed and the second strike is partly or fully obstructed.
This broadstruck 1994 Argentina 10 centavos shows an unobstructed first strike. The second strike was almost fully obstructed on the reverse face by what seems to have been a floating encrustation. The reverse face was struck by the hammer die. First-strike elements are flattened, but retain sharp margins. The only second-strike element to emerge is the C of CENTAVOS. The irregular texture and indistinct margins of the struck-through area are consistent with a floating encrustation.
This double-struck 2003 India 1 rupee coin shows an unobstructed first strike. The second strike was fully obstructed on the reverse face, which was struck by the anvil die. The minimal flattening of the first-strike elements and the variable depth and topography of the impression are inconsistent with a uniface strike against another steel 1 rupee planchet. I suspect a dollop of stiff grime entered the striking chamber and somehow found itself between the anvil die and the off-center coin on top. The subsequent strike flattened the crud deposit into a disc-like shape.
Foreign Object Chain Strike
Part IV. Striking Errors:
Foreign Object Chain Strike
Definition: A conventional chain strike occurs when the expanding edges of two adjacent discs of coin metal (2 planchets, 2 coins, or one of each) meet and flow together. A foreign object chain strike occurs when the edge of a coin metal disc and the edge of a foreign object meet and flow together. Right now, the only recognized foreign object chain strikes involve one member of a pair of feeder/ejection fingers that extend from the same feeder arm. These errors can therefore also be classified as a form of machine part impingement. Foreign object chain strikes involving other intrusive elements would be hard to recognize, unless they left a tell-tale residue on the edge of the coin or if they left the chain-struck edge with a very peculiar shape and/or texture.
The vast majority of foreign object chain strikes co-occur with a form of intra-strike damage at the opposite pole produced when the protruding portion of the off-center coin is pushed into the other feeder/ejection finger.
Most foreign object chain strikes are seen in multi-struck coins. These are invariably struck by inverted dies installed in the high-speed Schuler press.
This off-center dime shows a foreign object chain strike on the right side. Here the edge of the dime and the internal edge of a feeder/ejection finger met and flowed together. The edge of the dime is slightly convex and bears a 13 millimeter long contact facet. The opposite pole was pushed in when the protruding portion of the off-center coin was pushed into the other feeder/ejection finger. This form of intra-strike damage almost always accompanies a foreign object chain strike. The two together form a pattern of bilateral machine part impingement.
This quadruple-struck nickel shows a foreign object chain strike on the right side. Here the expanding edge of the nickel met the expanding edge of a feeder/ejection finger, leaving the former with a relatively straight edge. At the opposite pole we again see impact damage from the other feeder/ejection finger.
Two Anvil Dies / Foreign
PART III. Die Installation:
Mules:
Two anvil dies
Definition: Mules are coins struck by mismatched dies.
The 1982 Jamaica cent shown below displays the obverse design on each face. Since Jamaica is a former British colony the obverse design was probably struck by the anvil die. The U.K. and its former colonies typically use the obverse die as the anvil die.
The obverse design on the Chilean 100 pesos bi-metallic coin shown below is carried by the anvil die. One properly installed anvil die was paired with a second anvil die acting as the hammer die. Only one example of this mule is currently known.
The images below show a 1 EURO cent — country of origin and date unknown — that was struck with two reverse (anvil) dies.
Images are courtesy of Heritage Auctions.
Struck Through Hardware
PART VI. Striking Errors:
Struck Through Errors:
Struck Through Hardware
Definition: When it comes to foreign objects finding their way into a coinage press, almost anything goes. Bolts, screws, washers, and machine parts such as a feeder finger are occasional targets. Any coin trapped between a die and any of these objects is severely traumatized.
This off-center 1982 cent was struck through a threaded bolt on the left side. The left side of the coin was pinched off and lost as a result of the impact.
Coin courtesy of Sean Reynolds.
Struck Through Clad Layer
PART VI. Striking Errors:
Struck Through a Foreign Object:
Struck Through a Clad Layer
Definition: This error type occurs when a detached clad layer and an intact planchet enter the striking chamber together. The ensuing strike leaves one face with a shallow indentation and blurred design details in the floor of the indentation.
The 1969 Kennedy half dollar pictured below was struck-through a clad layer that entered the striking chamber on top of the planchet represented by this coin. Coverage was incomplete, leaving the coin with a large, shallow indentation and blurred design details.
Images are courtesy of Heritage Auctions.
- 1
- 2
- 3
- …
- 6
- Next Page »