I'm guessing plastic. Maybe a soft plastic but plastic none-the-less. The edge spot smears and lack of clay transfer to the lighter colors is kind of a give away. The outside edge of the chips edgespots (especially onto the lighter colors) usually smear when lathed down. The edges look so damn sharp so whether sanded or lathed clay would have smeared where as plastic has a higher melting temp.
The same company that was selling them in 2013, I see.
@maxim_666666 - I'm not sure whether they're china clays or plastic chips similar to Nexgen. The latter is more likely, IMO, because the price point is the same; china clays would probably cost a bit more. At 9.5g they're not slugged, so that's a point in their favor. One thing for sure -- they are not genuine clay compression molded chips like chips made by Paulson, CPC, or BCC.