We just love this stone although the rough is SO expensive and hard to find in quality. It is an opalized and agatized stone from beryllium ore which is called bertrandite. It is colored by the presence of fluorite. It comes, rightly so, from a beryllium mine in or near Delta, Utah. This is the only place on the planet this stuff comes from, and we're told that it comes primarily from the lunch buckets of the mine workers. This could just be lore, but that's what I hear. I buy it from collectors and stone dealers who are closer to the action. The featured picture is the core of a 30 pound chunk sitting on my deck. It has about a pound or two of good cutting in it.