Classification of Metamorphic Rocks

Questions and Answers

Metamorphic rocks are classified on the basis of?

Location and size

Age and origin

Color and weight

Composition and texture (correct)

What is foliation in metamorphic rocks?

Any planar fabric element

What is lineation?

Any linear fabric element

Define schistosity.

Aligned minerals are coarse grained enough to see with the unaided eye Signup and view all the answers

What does gneissose mean?

Either a poorly-developed schistosity or segregated into layers by metamorphic processes Signup and view all the answers

Describe slate.

Compact, very fine-grained, metamorphic rock with a well-developed cleavage. Signup and view all the answers

What characterizes phyllite?

A schistosity with very fine phyllosilicates imparting a silky sheen. Signup and view all the answers

Can phyllite be foliated and linear?

True Signup and view all the answers

What is gneiss?

A metamorphic rock displaying gneissose structure Signup and view all the answers

Define granofels.

No preferred orientation Signup and view all the answers

What is hornfels?

A type of granofels that is typically very fine-grained and compact. Signup and view all the answers

What is marble predominantly composed of?

Calcite or dolomite Signup and view all the answers

What is quartzite?

A metamorphic rock composed predominantly of quartz. Signup and view all the answers

What characterizes amphibolite?

Dominated by hornblende and plagioclase Signup and view all the answers

What is eclogite composed of?

Clinopyroxene and garnet Signup and view all the answers

Define blueschist.

A blue amphibole-bearing metamorphosed mafic igneous rock. Signup and view all the answers

What is serpentinite?

An ultramafic rock metamorphosed at low grade containing mostly serpentine Signup and view all the answers

What is porphyroblastic?

A metamorphic rock has one or more metamorphic minerals that grew much larger than the others. Signup and view all the answers

What does the prefix 'ortho-' indicate?

An igneous parent Signup and view all the answers

What does the prefix 'para-' indicate?

A sedimentary parent Signup and view all the answers

Study Notes

Classification of Metamorphic Rocks

Metamorphic rocks are categorized based on composition and texture.

Key Terms and Definitions

Foliation: A planar fabric element in metamorphic rocks.
Lineation: A linear fabric element observed in the structure of metamorphic rocks.
Schistosity: Characterized by aligned minerals visible to the naked eye, indicating coarse grain.
Gneissosity: Exhibits poorly-developed schistosity or is layered due to metamorphic processes.

Types of Metamorphic Rocks

Slate: A compact, very fine-grained rock with prominent cleavage, possessing dull freshly cleaved surfaces.
Phyllite: Contains schistosity with fine phyllosilicates that provide a silky sheen, although the minerals are not typically visible to the naked eye.
Gneiss: A metamorphic rock with a distinctive gneissose structure, marked by bands of different minerals.
Granofels: Lacks preferred orientation, resulting in a more homogeneous appearance.
Hornfels: A type of granofels, typically fine-grained and compact, usually found in contact aureoles from thermal metamorphism.
Marble: Composed primarily of calcite or dolomite, often formed from limestone or dolostone protoliths.
Quartzite: Dominantly made up of quartz, usually derived from sandstone protoliths.
Amphibolite: A metamorphic rock rich in hornblende and plagioclase minerals.
Eclogite: Notable for its green and red coloration, containing clinopyroxene and garnet, typically originating from basalt.
Blueschist: Characterized by blue amphibole; formed from metamorphosed mafic igneous rock or mafic graywacke.
Serpentinite: An ultramafic rock altered at low grades, largely comprising serpentine.

Special Characteristics

Porphyroblastic: Describes rocks with one or more large metamorphic minerals called porphyroblasts that grow significantly larger than surrounding crystals.

Prefixes Indicating Parent Material

Ortho-: Prefix used for rocks with an igneous parent origin.
Para-: Prefix indicating a sedimentary parent material.

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Description

Explore the classification of metamorphic rocks based on their composition and texture. Learn about key terms such as foliation, schistosity, and various types including slate, phyllite, and gneiss. This quiz will enhance your understanding of the fundamental characteristics that differentiate these rocks.