Help ID this Jade/Soapstone Seal

[dw171]

I bought this stamp/seal thing at an auction for a really cheap price. I'm not sure if its jade or soapstone. I've heard people tell me either one. Since I can't read Chinese I have no idea what it says besides DUKE. There appears to be a dragon carving on the top. If anybody knows anything about this I'd greatly appreciate more information. Thanks

 

[rock]

Well it looks interesting. Maybe somebody will know I will bump it back to the top for you.