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How Geologists Classify Rocks
Geologist classify according toTEXTURE
• Texture is the look and feel of a rock’s surface.• Texture can be described as– fine grained – with small particles
– Coarse grained – with large particles
– Glassy – no visible grain
Geologists classify according to Origin
• Igneous – forms from cooled magma or lava• Sedimentary –forms from particles of other
rocks or the remains of plants and animals that have compacted and cemented.
• Metamorphic – forms from rock that has been changed due to heat and pressure deep below earth’s crust.
IGNEOUS
• Igneous – forms from cooled magma or lava
Sedimentary
forms from particles of other rocks or the remains of plants and animals that have compacted and cemented.
Metamorphic
– forms from rock that has been changed due to heat and pressure deep below earth’s crust.
Geologists classify rocks according to Mineral composition
• Microscopes can be used to see crystal shape and structure
• Acid test can be used to test for carbonates
• Magnet test can be used to test for iron or nickel