Chinese Jade(?) Stamp Seal Chop Shoushan Whatever

Looks a little old to me, and definitely used a lot. Don't know if its white jade or not, but probably not. It was only a dollar though.

The estate had other very old, very valuable Asian antiques, like that gigantic yellow palace vase I posted earlier. Just wondering if anyone knew if this was authentic, and white jade or some other hardstone

Thanks for looking!
Still