These
fibrous crystals of Chalcanthite formed by seepage of ground water through
copper bearing minerals and then evaporation of the water in the dry environment
of a mine in Arizona.
Deep blue Chalcanthite crystals
in a parallel stack of fibrous crystals.
CHEMISTRY CuSO4 .5H2O Hydrous copper sulfate
CRYSTALLOGRAPHY Triclinic
CRYSTAL GROWTH AND HABITS Pinacoidal or tabular crystals are common, but Chalcanthite may also massive or stalactitic Crystals of Chalcanthite may also take on a fibrous appearance.
COLOR AND OTHER OPTICAL PROPERTIES Chalcanthite is typically azure blue; transparent to translucent.
HARDNESS 2.5
SPECIFIC GRAVITY 2.1 - 2.3
LUSTER Vitreous
STREAK Light blue
BREAKABILITY Conchoidal fracture and brittle, traces of three directions of cleavage
OCCURRENCE Chalcanthite is found in arid environments as a result of groundwater leaching through copper sulfides and then deposition of the mineral in open areas like caves or mine shafts.
ASSOCIATED MINERALS Gypsum, Calcite
OTHER Has a metallic taste and is soluble in water... NOTE that it is poisonous and is used as an insecticide.