Chemical composition -- A hydrosilicate of copper and aluminum.
Color -- Blue to green.
Optics -- R.I. 1.58-1.64.
Durability -- Hardness 2-4.
Crystal structure -- Monoclinic, cryptocrystalline.
Specific Gravity -- 2.20.
Sources -- Found in copper mines in the southwestern U.S. and elsewhere, often mixed with turquoise, malachite, azurite, and other copper compounds. Pure chrysocolla is too soft for jewelry purposes, but it often occurs in a highly silicified (cryptocrystalline quartz) form that makes magnificent robin's-egg blue cabochons.