Chalcophyllite

At one time chalcophyllite from Wheal Tamar in Cornwall, England, was called tamarite, but this name is now discredited[2] (not to be confused with the amphibole mineral taramite, which is quite different).

At Wheal Gorland a specimen exhibiting partial replacement of liriconite, Cu2Al(AsO4)(OH)4·(4H2O), by chalcophyllite has been found.

[2] The mineral is named from the Greek, chalco "copper" and fyllon, "leaf", in allusion to its composition and platy structure.

The difference reflects the fact that the water content varies at room temperature based on relative humidity.

Chalcophyllite is an uncommon secondary mineral occurring in the oxidized zones of some arsenic-bearing hydrothermal copper deposits.

Associated minerals include azurite, malachite, brochantite, chrysocolla, spangolite, connellite, cuprite, cyanotrichite, strashimirite, parnauite, lavendulan, cornubite, langite, clinoclase, pharmacosiderite and mansfieldite.

Chalcophyllite from Lemhi County, Idaho