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Classifying Rocks. 6.E.2.1 Summarize the structure of the Earth , including the layers, the mantle and core based on the relative position, composition and density. Rocks.
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Classifying Rocks 6.E.2.1 Summarize the structure of the Earth, including the layers, the mantle and core based on the relative position,composition and density.
Rocks • Are made of mixtures of minerals and other materials, although some may contain only a single mineral. • Granite • Quartz • Feldspar, • Mica • Hornblend
When examining a rock, you must look at the inside of the rock because the effects of ice, liquid water, and weather can change the outer surface of the rock. When studying a rock sample, geologists observe the rock’s mineral composition, color, and texture. Rocks
About 20 minerals make up most rocks of Earth’s crust. The minerals are known as rock-forming minerals. A rock’s color provides clues to the rock’s mineral composition. For example, granite is generally a light-colored rock that has high silica content. Basalt is a dark-colored rock that is low in silica. Mineral Composition
Mineral Composition • Geologist observe the shape and color of crystals in a rock to identify the minerals that the rock contains. • In identifying rocks, geologists also use some of the tests that are used to identify minerals. • Acid tests are used to test for carbonates. • Magnetic tests are used to test for iron and nickel.
As with minerals, color alone does not provide enough information to identify a rock. But a rock’s texture is very useful in identifying a rock. Most rocks are made up of particles of minerals or other rocks, which geologists call grains. Grains give a rock its texture. To a geologist, a rock’s texture is the look and feel of the rock’s surface. Some rocks are smooth and glassy. Others are rough or chalky. Texture
Texture • Size, shape and pattern of rock grains. • Grains- particles of minerals or other rocks.
Texture (Grain Size) • Course Grained-Large and easy to see. • Fine Grained-small.
Texture (Grain Shape) • Grains vary widely. • Tiny particles of sand. • Look like seeds • Crystals • Smooth / rounded • Jagged
Texture (Grain Pattern) • Grains often form patterns. • Some lie in flat layers. • Rows of grains. • Random grains.
Texture (No Visible Grain) • Have no grain. • They cool very quickly when they form, gives the rock a smooth, shiny texture like thick glass. (obsidian) • Or made out of extremely small particles of silica that settle out of water. (flint)
Origin • 3 Groups- refers to how the rocks formed.
Rock Cycle Igneous Sedimentary Pressure Metamorphic Molten Material
Questions A rock’s _________ provides clues to the rock’s mineral composition. A. shape B. size C. color D. diameter
What gives a rock its texture? A. Grains B. Color C. Size D. None of the above
What the three basic types of rocks? A. Microscopic, Normal, & Gigantic B. Igneous, Settlement, & Metamorphic C. Igneous, Sedimentary, & Metabolism D. Igneous, Sedimentary, & Metamorphic