Regents Earth Science
Igneous Rocks
Time 78 min
Name ___________________
Date Started ________________
Due date _________ Period ___
Igneous Rock Lab
Equipment: Igneous rock collection #1-12, hand lens, ESRT, text book
Objective: to practice classifying, identifying and describing various environments of formation.
Environment of formation: example: basalt is formed when molten material rich in Plagioclase
feldspar and Pyroxene solidify quickly, probably at the surface in a lava flow.
Procedure:
Observe each of the rocks with a hand lens. Note texture, presence of key minerals or other
characteristics in which to give a clue to the environment of formation. Show your notes
below:
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Open your E.S.R.T. to page 6 and notice the Scheme for Igneous Rock Identification data
table. Review the environment of formation for the rocks (ex. Peridotite is a coarse textured,
intrusive igneous rock that was formed deep within the Earth ). Align the igneous rocks in
your kit to the data table to see the relationships between the rock characteristics and the
environment of formation.
Questions: Please answer all questions in complete sentences. Use the index of the text to
find out about particular rocks, as well as the ESRT. Use on-line resources. Example:
Google the term “pegmatite”, see what kind of pictures and information are revealed.
1. How is Obsidian similar to Granite? (ESRT p. 6)
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ES Igneous Rock Lab 11.2013
Over 
2. Why is a Pegmatite non vesicular? Include the environment of formation (ESRT p.6)
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3. What is the grain size (mm) of Andesite? (ESRT p. 6) ____________________________
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4. How is the composition of Rhyolite similar to Gabbro? (ESRT p. 6) _________________
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