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Types of Metamorphic Rocks

Gneiss
Gneiss

Gneiss is a foliated metamorphic rock identified by its bands and lenses of varying composition, while other bands contain granular minerals with an interlocking texture. Other bands contain platy or elongate minerals with evidence of preferred orientation. It is this banded appearance and texture - rather than composition - that define a gneiss.

source: geology.com
Hornfels
Hornfels

Hornfels is a fine-grained metamorphic rock that was subjected to the heat of contact metamorphism at a shallow depth. It was “baked” by heat conducted from a nearby magma chamber, sill, dike, or lava flow.

source: geology.com
Marble
Marble

Marble is a metamorphic rock that forms when limestone is subjected to the heat and pressure of metamorphism. It is composed primarily of the mineral calcite (CaCO 3) and usually contains other minerals, such as clay minerals, micas, quartz, pyrite, iron oxides, and graphite.

source: geology.com
Novaculite
Novaculite

Novaculite is a dense, hard, fine-grained siliceous rock that breaks with a conchoidal fracture. It forms from sediments deposited in marine environments where organisms such as diatoms (single-celled algae that secrete a hard shell composed of silicon dioxide) are abundant in the water.

source: geology.com
image: geology.com
Phyllite
Phyllite

Phyllite is a very common metamorphic rock, found in many parts of the world. It forms when sedimentary rocks are buried and mildly altered by the heat and directed pressure of regional metamorphism. These are almost always convergent plate boundary environments involving continental lithosphere.

source: geology.com
Quartzite
Quartzite

Quartzite is a nonfoliated metamorphic rock composed almost entirely of quartz. It forms when a quartz-rich sandstone is altered by the heat, pressure, and chemical activity of metamorphism. These conditions recrystallize the sand grains and the silica cement that binds them together.

source: geology.com
Schist
Schist

This metamorphic environment is intense enough to convert the clay minerals of the sedimentary rocks into platy metamorphic minerals such as muscovite, biotite, and chlorite. To become schist, a shale must be metamorphosed in steps through slate and then through phyllite.

source: geology.com
Slate
Slate

Slate is a fine-grained, foliated metamorphic rock that is created by the alteration of shale or mudstone by low-grade regional metamorphism. It is popular for a wide variety of uses such as roofing, flooring, and flagging because of its durability and attractive appearance.

source: geology.com
image: nwnature.net