These are bars of solid gold, each one of which will become 400 Ultra-High Relief (UHR) Saint-Gaudens Double Eagles later in the year, when struck at the West Point Mint. These bars were part of the U.S. Mint's UHR exhibit at the 2008 ANA World's Fair of Money in Baltimore. The display text reads:
The United States Mint procures gold bars for the production of gold coins from refiners who acquire newly minted gold ore from sources in the United States. This gold must be .9999 grade or higher (24-karat) and fabricated into a standard bar of 400 +/- 50 troy ounces that is marked with the fineness, the melt number and/or bar number for identification and weight, and a recognized hallmark.
Each U.S. gold bar weighs about 27.4 pounds. The July 22, 2008 "London Fix" closing price of gold was $961.50 per troy ounce, making each bar worth about $384,645 on that date.
Based on the July 22, 2008 London Fix, the total value of the six bars on display is approximately $2,307,870.
If you think this is neat, the thing in the next display case will really excite you (see next photo...)