Provides a primary presentation of the basic rock types. Includes
five each of igneous, sedimentary and metamorphic rocks, totaling 15 specimens,
approximately 1 1/2" x 1 1/2".
This rock collection contains fifteen rocks that are
representative of the three major rock types: Igneous, Sedimentary and Metamorphic.
IGNEOUS ROCKS are formed by the cooling of molten rock,
either magma or lava.
1. OBSIDIAN is a black or brown volcanic rock composed of
quartz and alkali feldspar.
2. GRANITE is a medium to coarse-grained rock derived from magma and is composed primarily
of the minerals quartz and alkali feldspar.
3. BASALT is a microcrystalline dark colored lava rock composed mainly of calcic
plagioclase and clinopyroxene.
4. SCORIA is a dark colored, vesicular, crust on the surface of lava. The vesicles are the
result of escaping gas before solidification.
5. RHYOLITE is a usually light colored lava rock that is of the same composition as
granite.
SEDIMENTARY ROCKS are rocks derived from preexisting
rocks through the processes of erosion, followed by compaction, or chemical precipitation.
6. SHALE is a rock composed of clay, silt, or mud sized
particles that is typically fissile.
7. TRAVERTINE is derived from the evaporation of spring water from rivers, waterfalls, or
caves rich in calcium carbonate.
8. SANDSTONE is essentially sand-sized particles cemented together by calcite, silica, or
iron oxides.
9. CONGLOMERATE is a coarse-grained rock composed of rounded fragments set in a
fine-grained matrix of sand or silt or other cementing materials.
10. LIMESTONE is a generally light colored rock composed mainly of calcium carbonate
formed by either organic or inorganic processes.
METAMORPHIC ROCKS are rocks that are recrystallized by
pressure and heat that may or may not be influenced by the introduction of chemically
active solutions.
11. SLATE is metamorphosed shale and can be broken along
planes independent of original bedding planes.
12. MARBLE is recrystallized limestone (calcite).
13. QUARTZITE is a recrystallized sandstone or chert consisting mainly of quartz.
14. GNEISS is a metamorphosed rock that exhibits alternate banding of granular mineral and
flaky minerals.
15. SCHIST is a metamorphosed shale or siltstone composed of parallel
aligned micas, amphiboles, pyroxenes or garnets.
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