Metamorphic Rocks

2006 Prentice Hall Science Explorer- Earth Science

Liz LaRosa http://www.middleschoolscience.com 2009

Images from Geology.com unless otherwise noted

Metamorphic Rock

Metamorphic comes from the Greek word meta, meaning “change” and morphosis meaning “form”.

Heat and pressure deep beneath Earth’s surface can change any rock into metamorphic rock.

When rock change into metamorphic roc, its appearance, texture, crystal structure, and mineral content change.

Metamorphic rock can form out of igneous, sedimentary, or other metamorphic rock.

http://www.fi.edu/fellows/payton/rocks/create/metamorph.htm

Sometimes forces inside Earth can push the rock down toward heat in the mantle.

Pockets of magma rising through the crust also provide heat that can produce metamorphic rocks.

The deeper a rock is buried, the greater the pressure many times greater than the Earth’s surface, the minerals in a rock can be changed into other minerals.

Types of Metamorphic Rock Geologists classify metamorphic rocks

according to the arrangement of the grains that make up the rocks.

Foliated- metamorphic rocks that have their grains arranged in parallel layers of bands. Ex- slate, schist, and gneiss.

Non-foliated- metamorphic rocks that have mineral grains arranged randomly.Ex- marble, quartzite

Foliated - contain aligned grains of flat minerals in parallel layers or bands

Gneiss is foliated metamorphic rock that has a banded appearance and is made up of granular mineral grains.

It typically contains abundant quartz or feldspar minerals.

Non-Foliated – mineral grains are not arranged in plains or bands, just random.

Marble is a non-foliated metamorphic rock that is produced from the metamorphism of limestone.

It is composed primarily of calcium carbonate.

Determine if the following rock samples are foliated or non-foliated:

Amphibolite Quartzite Phyllite

Foliated

Contact Metamorphism – heated by nearby magma

Increased temperature changes the composition of the rock, minerals are changed into new minerals.

Hornfels is a fine-grained non-foliated metamorphic rock produced by contact metamorphism http://www.windows.ucar.edu/tour/link=/earth/geology/

meta_contact.html&edu=h igh&fr=t

Types of Metamorphism

Types of Metamorphism

Regional Metamorphism – pressure builds up in rocks that is deep within the Earth

Large pieces of the Earth’s crust collide and the rock is deformed and chemically changed by heat and pressurehttp://www.windows.ucar.edu/tour/link=/earth/geology/

meta_regional.html&edu=high&fr=t

Types of Metamorphism

Uses of Metamorphic rock

Marble and slate are two of the most useful metamorphic rock.

Marble is is mostly used for building and sculpture. Lincoln Memorial in Washington, D.C. is made of gleaming white marble.

Slate comes in a variety of colors, including gray, black, red, and purple. Because it is foliated, slate splits easily into flate pieces. These pieces can be used for flooring, roofing, outdoor walkways, chalkboards, and as trim for stone buildings.