Metamorphic Rock Identification
Introduction:
The Word “metamorphic” comes from Greek words meaning to change form
(mets – change, morphe = form). Metamorphic rocks are those that have formed from
other rocks as a result of the action of heat, pressure, and/or chemical action. Generally,
metamorphic rocks are divided into two groups: REGIONAL metamorphic rocks and
CONTACT metamorphic rocks.
Regional metamorphic rock is formed by forces acting over wide areas under
extreme conditions of temperature and pressure at great depths.
Contact metamorphic rocks are formed at the interface of hot magma and existing
rocks. The surrounding rock is changed, or metamorphosed, as a result of being in
contact with hot magma.
Objective: After you have completed this investigation, you should be able to:
1. Recognize metamorphic type rocks.
2. Identify several common metamorphic rocks.
Materials:
Gneiss
Slate
Marble
Quartzite
Schist
Magnifying lens
Procedure:
1. Use photographs or diagrams in your textbook for reference.
2. Divide the 5 metamorphic rocks into two groups, foliated and non-foliated:
Foliated
Has minerals arranged in bands or
layers and/or
May have light and dark colored bands
or flakes of different minerals and/or
May not have visible crystals and/or
May look like shale.
Non-Foliated
Minerals are NOT arranged in bands,
layers or flakes and/or
Usually monomineralic so it is one
color but it may have colorful veins
running through it but not as bands or
layers.
3. When you have your teacher’s approval, start with the non-foliated samples.
4. Complete the Report Sheet using you samples and the Scheme for Metamorphic
Rock Identification located in the Earth Science Reference Tables.
5. When you have identified the non-foliated samples, raise your hand to have your
teacher check your identifications.
6. Put your rock samples away and complete the lab report by answering the
questions.