CHALCOPHYLLITE, MALACHITE, CUPRITE, Redruth Cornwall England (LARGE CABINET)

Chalcophyllite is a rare secondary mineral composed of copper arsenate, typically found in the oxidized zones of certain arsenic-rich copper deposits. Initially identified from samples in Germany, it was previously referred to as tamarite when sourced from Wheal Tamar in Cornwall, England, although this designation is now obsolete and should not be confused with the distinct amphibole mineral taramite. The name chalcophyllite derives from the Greek words for "copper" and "leaf," highlighting its composition and layered structure. The literature presents two different chemical formulas for chalcophyllite: Cu18Al2(AsO4)4(SO4)3(OH)24·36(H2O) with a molar mass of 3098 g, and Cu18Al2(AsO4)3(SO4)3(OH)27·33(H2O) with a molar mass of 2956 g, indicating variability in water content influenced by ambient humidity.

Malachite is a mineral composed of copper carbonate hydroxide, represented by the chemical formula Cu2CO3(OH)2. This opaque mineral features distinctive green bands and crystallizes within the monoclinic system. It typically forms in botryoidal, fibrous, or stalagmitic shapes in fractures and subterranean environments, where the presence of hydrothermal fluids and the water table facilitate chemical precipitation. While individual crystals are uncommon, they can appear as slender or acicular prisms, and pseudomorphs resembling more tabular or blocky azurite crystals are also found.

Cuprite is a copper(I) oxide mineral, specifically Cu2O, and serves as a minor source of copper. It features dark crystals that exhibit red internal reflections and belongs to the isometric system's hexoctahedral class, presenting in cubic, octahedral, or dodecahedral shapes, often in various combinations. Penetration twins are a common occurrence. Despite its attractive color, cuprite is seldom utilized in jewelry due to its relatively low Mohs hardness of 3.5 to 4. It possesses a high specific gravity of 6.1, exhibits imperfect cleavage, and is brittle with a conchoidal fracture. The mineral's luster ranges from sub-metallic to brilliant adamantine. The "chalcotrichite" variety, derived from Ancient Greek meaning "plush copper ore," is characterized by elongated, needle-like crystal formations that are aligned parallel to the [001] direction.