I’ll give you a hint as this is not a common form. It’s soft enough to cut and carve with hand tools such as a knife, file and sand paper. It’s not talc nor is it soapstone. It’s fairly simple to finish it to a high glossy/glassy sheen.
There was a small lode of it by the side of an old highway leading to Lake Roosevelt, Arizona. Sadly, when the road was widened, the lode was destroyed.
Sorry about the fuzzyness. Still not good with a camera.
So, what do you think it is?