Not authentic THC like others have said. I have a set of these. They are extremely lightweight (i.e. no metal slug), inexpensive chips. I'd value them at around 5 cents a chip. To others, they're not even worth that.
They are a very unique material -- hard, but very lightweight, plastic-ceramic-like material, and colors will vary and fade (which makes them appear like they might be clay chips in photos), but most chips will also darken if oiled with mineral oil, unlike any other plastic chip I've ever seen.
One use for them in my opinion, due to the extreme light weight, they would make a great long-distance travel set, for taking on a vacation, cruise, etc. It's also a set that you're not worried if a chip gets lost.