I would guess some type of quartz. Polished by wave action. I bet if you put it in a rock tumbler it would turn out to be a real beauty, from the color.
DG
That's a beautiful gemstone. It might be lepidolite (lipidolite) which is a Lithium bearing rock and has the same 'thin layer' type of construction which seems to be on your stone. Cheers, Mike
Took it to several Jewelers. I got no definitive answers. A few of them thought it was some kind of dyed rock , but they couldn't tell me the type. The gemologist thought it was some type of agate dyed or something like that. None of them though is was precious. The mystery goes on.........
If it was whale barf otherwise known as ambergris it could be worth a few bob - but it isn't.
A picture of whale barf on this link, Cheers, Mike http://www.ambergris.co.nz/about.htm