metamorphic rock

Slate

Foliated metamorphic rock; very fine-grained; dull surface; low-grade metamorphism of shale.

Phyllite

Foliated metamorphic rock; silky or glossy sheen; wavy mica layers; intermediate between slate and schist.

Schist

Foliated metamorphic rock with visible mica or other platy minerals; medium to high grade.

Garnet Muscovite Schist

Schist containing abundant garnet and muscovite; indicates medium to high metamorphic grade.

Gneiss

Foliated, banded metamorphic rock; alternating light and dark mineral layers; highest grade of regional metamorphism.

Quartzite

Non-foliated metamorphic rock formed from sandstone; very hard; composed mainly of quartz.

Marble

Non-foliated metamorphic rock formed from limestone or dolostone; composed of calcite; reacts with acid.

Greenstone

Metamorphosed basalt; green color from chlorite, epidote, or actinolite; low-grade.

Amphibolite

Metamorphic rock dominated by amphibole (hornblende) and plagioclase; medium to high grade.

Garnetite

Metamorphic rock composed mostly of garnet; forms under high pressure and temperature.

Serpentinite

Non-foliated metamorphic rock made of serpentine minerals; formed from ultramafic rocks; green and slippery.

Hornfels

Fine-grained, non-foliated contact metamorphic rock; formed by heat from magma intrusions.

Actinolite

Green amphibole mineral; forms in low- to medium-grade metamorphism of mafic rocks.

Glaucophane

Blue amphibole mineral; indicator of high-pressure, low-temperature (blueschist) metamorphism.

Talc

Soft, greasy mineral (hardness 1); forms from ultramafic rocks; used in talcum powder.

Kyanite

Blue bladed mineral; forms under high pressure, low temperature; polymorph with sillimanite and andalusite.

Staurolite

Brown prismatic mineral; often forms cruciform twins; medium-grade index mineral.

Sillimanite

Needle-like mineral; forms under high-temperature metamorphism; polymorph with kyanite and andalusite.

Garnet

Red to brown mineral; common in schist; medium-grade index mineral.

Serpentine

Green, waxy mineral; forms by hydration of olivine in ultramafic rocks; component of serpentinite.

Tremolite

White to green amphibole mineral; forms from metamorphism of dolomite or impure limestone.

Chlorite

Green flaky mineral; forms during low-grade metamorphism of mafic rocks; gives greenish color to schists.

Andalusite

Columnar pink or gray mineral; low-pressure, high-temperature polymorph of Al₂SiO₅ group.

biotite

muscotive

hematite

calcite

k feldspar

na feldspar

amphibole