The rarest and most valuable of the chalcedony (kal-sed’-nee) group is the translucent, turquoise blue variety known as Gem Silica or Gem Chrysacolla. Technically this is a gem chalcedony, translucent crypto-crystalline quartz that is colored by traces of Chrysacolla, a copper mineral. This material is very rare and has largely been unavailable with virtually no new rough coming from traditional sources, copper mines in the American southwest, for over twenty years. Several years ago a new deposit of some exceptional Gem Silica was discovered by a local family man mining for bentonite clay in India, near the Indian - Cashmere border. I was fortunate that Mr. Arvind was able to locate me through the internet and we were able to negotiate the purchase of approximately one kilogram of the rough. The material is exceptionally translucent, very hard and durable like agate, and ranges in color from light blue to intense deep turquoise greenish blue.