Tuesday, March 20, 2007

Purple Rock mystery solved

It's lab-grown, chromium-bearing alum K(Al,Cr)(SO4)2 . 12H2O . The very nice people on the mindat message boards helped me out.

1 comment:

Tenney said...

Wow! That is amazing! Why did they grow that in a lab? It must be too soft to use as a gemstone.