9) Economically Important Minerals-I G 232

Hypogene and hydrothermal

Native elements
gold	Au	1) quartz veins, 2) placers	quartz, pyrite, chalcopyrite, galena, stibnite, sphalerite, arsenopyrite, tourmaline, molybdenite
silver	Ag	1) oxidized zones of ore deposits, 2) hydrothermal veins	sulfides and arsenides containing Co, Ni, As
copper	Cu	1) oxidized portions of copper deposits, 2) primary crystallization from fluids associated with mafic lava	silver, various sulfides, calcite, chlorite, zeolite minerals, cuprite, malachite, azurite
Sulfides
galena	PbS	1) common in many types of sulfide deposits	sphalerite, chalcopyrite, pyrite, fluorite, barite, marcasite cerussite, anglesite, calcite, dolomite, quartz, native silver, acanthite, pyrargyrite
sphalerite	ZnS	1) in voids within carbonate rocks, 2) hydrothermal veins, 3) contact metamorphic aureoles	galena, chalcopyrite, pyrite, barite, fluorite, carbonates, quartz, pyrrhotite, magnetite
chalcopyrite (kal-koe-pie-right)	CuFeS2	1) hydrothermal and replacement sulfide deposits, 2) magmatic segregations in mafic igneous rocks, 3) black shales	pyrite, sphalerite, bornite, galena, chalcocite, pyrrhotite, pentlandite
chalcocite (plus digenite) (kal-koe-sight)	Cu2-xS	1) primary or secondary copper ore mineral in veins and altered zones	bornite, chalcopyrite, enargite, galena, tetrahedrite, cuprite, pyrite
bornite	Cu5FeS4	1) sulfide-bearing hydrothermal veins, 2) secondary in enriched zones of sulfide deposits	chalcopyrite, chalcocite, covellite, pyrrhotite, pyrite
molybdenite (mu-lib'-den-ite)	MoS2	1) accessory minerals in some granitic rocks and pegmatites, 2) porphyry copper deposits, 3) vein deposits, 4) contact aureoles	scheelite, cassiterite, wolframite, fluorite, quartz
arsenopyrite (awr-seen'-oh-pie-right)	FeAsS	1) in veins with other metal ores, 2) in pegmatites, 3) contact aureoles, 4) disseminated in low- to medium grade metamorphic rocks	chalcopyrite, pyrite, sphalerite, cassiterite, gold and silver minerals