A velvety
mass of acicular crystals in a pocket in Limonite, from Morenci, Arizona.
A "spray" of Brochantite crystals
in Limonite.
A close up view of the above
picture.
CHEMISTRY Cu4(SO4)(OH)6
CRYSTALLOGRAPHY Monoclinic
CRYSTAL GROWTH AND HABITS Prismatic and found as acicular to stout prismatic crystals, also tabular. It can also form drusy masses or be massive and granular.
COLOR AND OTHER OPTICAL PROPERTIES Brochantite is light green to blackish green but most commonly emerald green, transparent to translucent.
HARDNESS 3.5 - 4
SPECIFIC GRAVITY 3.9 - 4.1
LUSTER Vitreous
STREAK Light green
BREAKABILITY Perfect cleavage in one direction, uneven to conchoidal fracture
OCCURRENCE Brochantite is a secondary mineral found in the deep oxidized zones of copper deposits, commonly in arid environments.
ASSOCIATED MINERALS Malachite, Azurite, Tenorite, Cuprite, Linarite, Limonite.