Minerals & Rocks: Metamorphic

Metamorphic rocks result from the subjection of a protolithic parent rock (igneous, sedimentary, or metamorphic) to heat and/or pressure and/or chemically active fluids. Metamorphic rocks are classified according to the parent rock and the degree of deformation to which the rocks have been subjected. Metamorphism occurs locally (contact) or on a large scale (regional).

Sedimentary rock	Metamorphic product (low to high grade)
Conglomerate	Meta-conglomerate, schist, gneiss
Breccia	Meta-breccia, schist, gneiss
Sandstone	Quartzite, mica schist
Shale/siltstone/claystone	Phyllite, slate, schist, gneiss, "fubarite"
Limestone/dolostone	Marble (color shows "argillaceous" or "carboniferous")
Black shale	Black slate
Peat/coal	Anthracite through graphite with or without associated natural gas, petroleum and asphalt; Mississippi-type lead and zinc deposits

Chemical metamorphic rocks:

Composition	Mineral Name	Rock Name/Ore
Au	Gold	Gold Ore
Ag	Silver	Silver Ore
Cu	Copper	Copper Ore
Pt	Platinum	Platinum Ore
S	Sulfur	Native Sulfur
CaF2	Fluorite	Fluorospar

Deposition of metals results from regional metamorphism, volcanism, hydrothermal vents, and sulphide solutions:

Composition	Mineral Name	Rock Name/Ore
PbS	Galena	Lead
ZnS	Sphalerite	Zinc
FeS2	Pyrite/Marcasite	Iron
(Cu,Fe)S2	Chalcopyrite	Copper

Solutions of hot water chemically alter carbonates and silicates:

Composition	Mineral Name	Rock Name
SiO2 transparent	...	Quartz, rock crystal
SiO2 translucent	...	Jasper, flint, chert, quartz, chalchedony, agate, silicified fossils, petrified wood
CaCO3	Calcite	Travertine marble, geodes, stalactites/stalagmites