Azurite, Malachite and Limonite

AZURITE, MALACHITE AND LIMONITE  

Guichi District, Anhui Province, China

specimen: 7 x 4 x 7 inches (17.8 x 10.2 x 17.8 cm)  

height with stand: 9 inches (22.9 cm)

Azurite is among the most visually compelling of the secondary copper minerals. Its deep blue coloration has made it a collector's mineral of long standing and, historically, a source of pigment — the blue of many medieval and Renaissance panel paintings was derived from ground azurite. Fine cabinet specimens from the Guichi District of Anhui Province are regarded among the best of their type, valued for the scale and density of their crystal development.

A substantial cabinet specimen presenting a dense cluster of deep prismatic azurite crystals with strong vitreous lustre, intergrown with bright green malachite and an ochre limonite matrix. Secondary microcrystalline azurite is present across the surface. The three-mineral association records a characteristic sequence of secondary oxidation in a copper deposit: azurite and malachite both forming as copper-bearing fluids interact with carbonate-rich host rock, with limonite developing from the oxidation of iron sulphides in the surrounding matrix.