Carl, In order to get rid of the old chips (because changes in ownership), the chips were sometimes buried in cement. The “burial” was most commonly done where there were new expansions to the casino (or when a new sidewalk was needed to be poured).

The Sand, Dunes and other casinos buried some of their chips.

What happens is when the casino is raised for a new mega resort; some of these chips are found and recovered. Some of these chips make it out in pretty good shape.

I’m sure some of the other experts can tell which casinos buried their chips.