Chalcophyllite

The Potrerillos mine in Chañaral Province, Atacama, Chile, worked a mineralized porphyry stock which intruded a sedimentary carbonate sequence of mid to late Mesozoic age.  This rich specimen of the copper-aluminium arsenate Chalcophyllite is a magnificent example of this quite rare species and covers two main areas measuring approximately 6 x 2 cm and 3 x 1.5 cm.  The Chalcophyllite forms an intergrown network of platy hexagonal crystals of its characteristic bluish-turquoise, commonly of 3 to 4 mm across.  Surrounding much of the Chalcophyllite is a dark leaf-green, micro botryoidal mineral.  Although this appears like duftite, this species is not listed as occurring at Potrerillos, so is more likely to be Malachite, especially given that the matrix in the base is criss-crossed by thin veinlets of Azurite.  A magnificent Chalcophyllite from Chile.