Introductory Rock Collection

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''. INTRODUCTORY ROCK COLLECTION 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 orig

• 15 specimens

• Specimens sized 1 1/2'' x 1 1/2''

• 5 each igneous, sedimentary, and metamorphic.