What is Koulz Alloy
by David Cassel
April 25, 2001
revised April 24, 2002

The following is a response sent by David Cassel to Alan Herbert of Numismatic News regarding the following “Some time ago you listed several coin-metal alloys. Do you have a listing for Koulz‘s alloy?”. See the revised addition at the bottom of this.

Dear Mr. Herbert:

My extensive spectrographic SEM-EDX analysis of 57 - US pattern Postage Currency coins culminated in my publication of United States Pattern Postage Currency Coins - a year ago. My analysis included the verification that at least one so called “Koulz’s alloy” coin exists. Possibly fifteen planchets may have been prepared but an uncertain number survive.

I am happy to offer my thoughts on the subject along with an excerpt extracted from my book dealing with the subject.

‘“An account of these strange coins should be added to your reading list. Both Judd and Pollock contain a most interesting account of Dr. Henry Linderman on the subject of Koulz’s Alloy. In Judd’s United States Pattern, Experimental and Trial Pieces, see pg. 105 and in Pollock’s United States Patterns and Related Issues see pages 182 and 183.

The next three paragraphs are how I catalogued the 1869 Koulz’s inspired dime of the Gene H. Wolfe Collection offered by Heritage Numismatic Auctions, Inc. at the F.U.N. convention, January 2000.

“A supposed German chemist, Koulz was the inspiration for both the first reverse design, ‘SIL.9’ over ‘NIC.1’ above a line which is over the date ‘1869’ and second reverse design elements, ‘SIL.’ over ‘NIC.’ over ‘COP.’ above a line which is over the slightly curved date ‘1869.’ An effort to garner some additional information on Koulz, proved fruitless. Regretfully, this cataloguer with the help of numismatists in Germany and the United States using the facilities of libraries, encyclopedias, and the Internet could come up with not a single reference to Koulz, not even his first name, except that in the 600 page German lexicon, Koulz may not be a German name.”

“What little we know originated in a booklet entitled Suggestions to Congress of the Finances of the United States submitted to the Chamber of Commerce of New York, by H. E. Moring, in 1869. This is where, more or less, from the earliest pattern book reference to Koulz found in the Adams and Woodin United States Pattern, Trial, and Experimental Pieces, published in 1913 and reprinted in 1959, Dr. Judd, Andrew Pollock and now this cataloger essentially restate what, according to Andrew Pollock III, in United States Patterns and Related Issues was offered:

‘In 1869 the Mint experimented with an alloy consisting of 41% copper, 33% nickel, and 26% silver. The alloy was invented by the German chemist, Koulz, and promoted by a New York chemist [and Metallurgist, Stefan] Krackowizer. Dr. Judd in his pattern book quotes the commentary of W. E. DuBois who describes the alloy as follows: ‘Mr. Eckfeldt made a small bar, and gave it three meltings. It rolled down with great difficulty, splitting and cracking in spite of all the precaution and annealings. Mr. Barber made a reverse to try it under the press (using the dime head for the obverse,) and a faint impression was produced in the steam press. The metal is totally unfit for coinage, and the color is bad.’ Director Pollock considered the ‘Koulz’s alloy’ coinage at some length in his Annual Report of the fiscal year ending June 30, 1869. ‘Under the coining press it was barely possible to produce a feeble impression, on account of the intense hardness, and danger both of breaking the dies and flawing the planchet. In short, nothing could be more unfit for coinage.’”

In my search for examples of Koulz’s alloy coins, I tested four coins that possibly had the attributes of a Koulz’s alloy coin. In the Judd numbering system there are two coins that are nearly impossible to distinguish as to whether they are Koulz’s alloy or simply cupro-nickel. They have identical designs for both the obverse and the reverse and were made from the same set of dies. J-716 represents the Koulz’s alloy coin and J-717a represents the cupro-nickel version that contains no silver. The difficult attribution is compounded by the fact that both versions weigh nearly the same and have nearly the same specific gravity: 9.45 for a cupro-nickel specimen and 9.32 for a Koulz’s alloy specimen.

Illustrating the weight as a defining characteristic in the attribution of J-716 vs. J-717a can be demonstrated by revealing the weight of the four tested examples. The weight ranged from a low of 44.60 grains (contained .05% silver,) 45.70 grains (contained 30.4% silver,) 45.94 grains (contained no silver,) and 46.60 grains (contained no silver.) The 44.60 grain coin is a hybrid J-716/717a in that it contains a small amount of silver but not enough to qualify as a true Koulz’s alloy coin. The 45.70 grain coin is a definite J-716. The 45.94 and 46.60 grain coins are definitely J-717a cupro-nickel coins having no silver.

Also the striking characteristics are similar to the untrained eye. To the trained eye, the cupro-nickel version appears to be not fully struck, as compared with the copper, similar coin, J-717. The Koulz’s alloy coin is less fully struck than the cupro-nickel version. The greater the proportion of silver to nickel, the poorer the amalgamation, the harder the planchet, the lower strike pressure than necessary for an optimal impression, hence, the poorer quality of the end product.

One coin that I tested weighing 46.60 grains contained copper 76%, nickel 23%, silver .05%, silicone .2% (used for its anti-oxidant qualities,) and iron .1% (Silicon is never found in nature in its pure form. The alloy known as ferro-silicon was used by the Mint to introduce the silicon into the amalgamation.) This coin, with its small amount of silver in combination with nickel, had a much better appearance (MS 66) than did the next.

The second example weighing 45.70 grains, a MS 64 coin contained copper 27.4%, nickel 42.1%, and silver 30.4%. This coin lacked the eye-appeal qualities of a gem but not due to mishandling. This coin qualifies, while not precisely the same formulation that we are led to believe as a Koulz’s alloy coin: copper 41%, nickel 33%, and silver 26% - is a Koulz’s alloy coin, for all intents and purposes. It is possible that owing to the fact that silver was nearly impossible to combine with nickel, the spectrographic analysis might have had proportional diversity if taken from a variety of locations on the coin’s surface.

I do not regard a Koulz’s alloy coin as a “billon” coin as you mentioned in your article for a technical reason. The definition of “billon” is: a primarily copper alloy coin with less than half its weight in silver. According to Webster’s Dictionary: “An alloy of silver with more than its weight of copper, tin, or the like.” For a coin to qualify as billon, it must have more than half its weight in copper and less than half its weight in silver.

When your article asked: “Any reader help on any coins actually struck in this combination of metals?”, I offer the foregoing. You may publish what I have written. I’ll appreciate your giving me credit for this information.


David Cassel

Additional research by David Cassel has determined that the name Koulz is a typo for Montchal Ruolz. For more on this, click here.