Can anyone help me find out the origin/material of this ornament?

This ornament was left for me by my late father, who used to be an antique dealer. I can't find any information on its origin (looks Thai but that's as much as I know!) and although my Dad had talked to me about buying it at an auction, I can't figure out what it's made of...stone, bronze?!

Any insight would be hugely welcome.

It's very very heavy,38cm high, 11cm deep & 12 cm wide.

Thanks