In ancient times, the state of Nevada was a scene of many gambling casinos, Gary. There are a number of archaeological digs in the area that turn up old chips from time to time, buried for eons by violent implosions. These chunks of rock have the appearance of concrete that has flowed around the chips.

You should talk to Howdy Herz of "Gaming Archaeology" in Minden sometime about the subject.
Don't tell him I sent you [g]!