Rolled-thin planchet: A coin struck on a planchet punched out of stock that was rolled too thin on the rolling mill.
This 1974 quarter was struck on a rolled-thin planchet. It weighs 4.92 grams instead of the normal 5.67 grams.
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Definition: A bristle from a wire brush used to scrape clean the dies. Because a complete wire bristle looks rather like a staple, they are often misidentified as such.
Below a 2000-P Maryland quarter with a rolled-in steel wire (bristle from a rotating descaling brush) The wire probably corresponds to a piece of what used to be called a “staple”, but which is now recognized as a bristle from a wire brush used to clean the dies of obstructing matter. Note that the wire has split the clad layer, something that doesn’t happen with a struck-in wire (at least among coins struck within the collar).
A 2000-P Maryland quarter with a long piece of steel wire embedded in the obverse. The wire runs beneath the outer clad layer as it skirts the word UNITED. The tip of the wire reemerges for a short distance before terminating (red arrow). The clad layer has split along the path of the wire, exposing the copper core. The copper core is also exposed along and just inside the rim, possibly indicating the presence of a second wire that lay just outside the area sliced through by the blanking die.
Definition: A foreign object is rolled into the coin metal strip and falls out after the strip is rolled to final thickness.
The object can remain embedded in the subsequent blank or planchet but falls out before the planchet arrives at the coinage press. The result is an underweight blank that has a recess on one face. When struck, the coin displays that same recess and also shows weakness in the same area on the opposite face.
This 1980 cent shows a bowtie-shaped rolling indentation on the reverse face. The indentation is too elongate to represent the impression of a bowtie clip planchet or a piece of chopped webbing. The obverse face shows weakness opposite the recess. The coin weighs 2.79 grams, significantly less than the 3.1 grams of a normal copper-alloy cent.
For more information on this error type see the February 7, 2011 Coin World.
Definition: In a rotated die error, one of the dies spins around its vertical axis. In the case of a normal, in-collar rotated die error, it is impossible to determine which die has rotated. Complex and compound rotated die errors where the die rotation is combined with at least one other error do allow us to determine which die rotated. In the vast majority of cases, the hammer die is the culprit.
Rotated die errors can come about in at least three ways.
Die rotation errors can be stable or dynamic. Stable rotated die errors produce coins that show the same amount of rotation in each coin that is struck. This 1994 cent shows a stable rotated die error. Relative to the obverse die, the reverse die shows a 165 degree counterclockwise rotation.
The dies that struck this 1980-S proof Lincoln cent were installed in the medallic position. In other words, the obverse face and the reverse face both point north.
Images are courtesy of Heritage Auctions.
Definition: When a rotated die collides with its normally-oriented companion, it leaves rotated clash marks on the opposite die. Naturally, the clash marks it picks up look rotated as well. Ordinarily it is impossible to determine which die was rotated. Only in the case of complex and compound rotated die errors is it possible to identify the culprit, and most of the time it is the hammer die.
This 1984 cent shows a modestly rotated set of clash marks, amounting to 15 degrees. The coin was struck while the die was still in its rotated position.
The bottom picture (the reverse of the coin) has been inverted and horizontally flipped to show the correct attitude of the die when the clash was created
Definition:If a mintmark punch is held in a rotated position, the letter punched into the face of the working die will reflect that. Most rotated mintmarks lean at an angle of no more than 10 degrees. Severely rotated mintmarks are inevitably repunched. The one exception applies to mintmarks that look almost the same when rotated 180 degrees. As a result, inverted S-mintmarks sometimes slip through quality control.
This 1987-D cent has a D-mintmark that is rotated a few degrees clockwise.
A nearly horizontal D-mintmark was corrected by a second punch in the proper orientation. Photo courtesy of Chuck Daughtrey and coppercoins.com
Discovered only a few years ago by BJ Neff, this 1946 cent carries an S-mintmark that is rotated 180 degrees.
Definition: Collars sometimes do rotate and this movement can only be detected if there is an imperfection in the collar that leaves a blemish on the edge of the coin.
In the July/August 2003 issue of Errorscope, William (“Ed”) Eubanks provided the definitive study of a rotating collar break (specifically a collar chip) on a large series of 2002-P Kennedy half dollars. In a sample of 261 half dollars, Ed showed the collar chip steadily rotating clockwise through a full 360 degrees. He tracked its movements across 9 die stages and 3 die pairings.
Note: The circumstances and mechanisms that lead to collar rotation remain obscure.
Edge view of two 2002-P Kennedy halves struck by the same die pair and within the same collar. The collar chip occupies a different position on each, relative to the coin’s design. This variable positioning documents the existence of a rotating collar or collar lining. Arrows point to the collar chips. Coins courtesy of Ed Eubanks.
Definition: This variety type occurs when a mintmark is punched into a working die and then repunched with the same letter, but with a different font style.
The above images show a 1947 Lincoln cent. A mintmark with serifs was over-punched with a sans serif mintmark. Notice the pronounced notch on the upper terminus of the S-mintmarks. The upper loop is the sans serif mintmark while loop just below it is the upper loop of the serif mintmark.
The images are courtesy of Coppercoins.
Definition: A die with a rusted or corroded surface. The roughened and pitted areas will be transferred to the coin as areas of raised metal.
This 1921(P) Morgan dollar shows patches of raised metal on the reverse face. This condition was probably caused by a rusty die.
Image is courtesy of VAMworld.