Mount Diablo Mine (Mt. Diablo Mine; Ryne Mine), Mount Diablo, Clayton, Contra Costa Co., California, USA
Small Cabinet, 8.4 x 5.4 x 3.4 cm
Metacinnabar, though rather rare, is actually chemically the same as cinnabar (HgS), and can actually be transformed into cinnabar upon heating to around 500 degrees centigrade. Specimens have come from Italy, Romania, and as in this case, from California. What is nice about this specimen is how the cluster of crystals is isolated on a matrix of small quartz crystals. This is an old piece out of the Burton Jirgl collection - now hard to obtain!