Group: Arsenates

Chemical composition: CaCu(AsO4)(OH)

Colors: Grass-green to yellowish green, pistachio-green, emerald-green; may be zoned

Hardness: 4.5

Formation: Crusts of acicular to almost fibrous crystals. Also as botryoidal masses and compact crusts.

Principal Sources: Utah, Nevada, Colorado, USA; Durango, Mexico; Chile; England; Spain; and Namibia

Special Notes: Conichalcite forms in the oxidation zones of copper orebodies. Here groundwater enriched with oxygen react with copper sulfide and copper oxide to produce an array of minerals such as malachite, azurite and linarite. Conichalcite is often found encrusted on to limonitic rocks that have yellow to red colors.