The information and photo are courtesy of Mike Byers.
This is an SBA Dollar struck on an experimental planchet similar to the ones found on the 1999 Experimental State Quarters were struck. These planchets are slightly different in composition from the mint errors struck on Sacagawea dollar planchets. One of these has the color of the Sacagawea dollar but does not have the copper center core. Another has a slight "green" color and has the copper center core. The third piece has a slight "green" color but does not have copper center core.
Here are some of the "tell tale" signs to determine if you have found a SBA Dollar on an experimental planchet in circulation:
WEIGHT - The weight of ALL of these discovered so far is
UNDERWEIGHT - varying from 7.3 grams to 7.6 grams.
SIZE - It is slightly THINNER than a regular SBA Dollar, due to the lighter planchet.
COLOR - So far, the pieces discovered are either the same "color" of the Sacagawea Dollar, or have a slight "green" color to them.
LOOK - The edge is slightly rough and may have a higher rim around part of the edge.
EDGE - Some of these do NOT have the center COPPER CORE.
STRIKE - None discovered so far are proof-like in the fields.
REEDING - Some of these have incomplete reeding.
LINT MARKS - One of these has several lint marks on both the obverse and reverse.
In a recent Freedom of Information Act (FOIA) request for copies of any reports and test results, the Department of the Treasury acknowledged that "the U.S. Mint conducted engineering and metallurgical tests as part of its development of an alloy for the Golden Dollar", but would not release any information.
PCGS has authenticated all three known pieces to date. The specimen photographed here is a SBA Dollar with a slight "green" color and a copper center core.
Editor's note: 2 of these have been analyzed. One with a greenish gold color was found to be 70% Copper, 28% Zinc and 2% Nickel. The second was
73% Copper, 25% Zinc and 2% Nickel. It is unclear if these are truly experimental pieces or some sort of mint error. It is very possible that these and the similar state quarters were deliberately struck using available experimental planchets for the Sacagawea dollar. We are listing them under mint errors as this sector of the collecting fraternity was the first to embrace these. We hope that further information into their true nature will appear in the future.