Hi, my doctor gave me that stone years ago. I don't know what it is, but an Hindu person asked me where I got it from and if I knew what it is used for. I have no idea what he was talking about. Does anyone knows what it is?
It's difficult to say from that photograph. If it shows iridescence (looks like it in the photo but may be a trick of the light) then I would guess it's some kind of feldspar, probably a labradorite.
No idea what it is used for, but many religions asign meanings to gemstones.