Hi Michael.Try contacting the people in this link I’m giving you:

http://minerals.er.usgs.gov/minerals/pubs/state/

There is bound to be someone who an tell you more about the stone.

Bill Oddie was taught by a very good lady guitarist, it’s just a pity he didn’t listen to her advice.
I have musicians in the family, and friends.They always say the same thing, practice, practice and more practice.
Invest in some guitar tuition too.
You will get sore fingers, but you’ll get over it.
You might find some good teaching dvd’s at your…[Read more]