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MINERALS http://www.youtube.com/watch?v= TYvye0CVbU0 Matter • anything that has mass and takes up space • Matter is composed of elements Element • A substance that cannot be broken down into simpler substances by ordinary chemical means Composition of Earth’s Crust ESRT Page 1 A grouping of atoms - Molecule Most common molecule in Earth’s crust • Silica Tetrahedron Composed of … 1 silicon atom 4 oxygen atoms Silica Structure 4 oxygen atoms for every 1 silicon atom Olivine Pyroxenes (Augite) Amphibole (Hornblende) Micas Feldspar, Quartz Complexity Temp. MINERALS • Naturally occurring • Inorganic (never alive) • Definite chemical composition • Crystal structure because of the internal arrangement of atoms A mineral is the building block of rocks Native Minerals – Made of single elements • Gold (Au) • Copper (Cu) • Sulfur (S) Compound Minerals – Made of two or more elements • Silicate Family – A compound of silicon and oxygen – 90% of the Earth’s crust is composed of silicates Examples: – Quartz SiO2 – Olivine (Fe,Mg)2Sio4 Graphite Diamond Chemical formula: C Chemical formula: C How can 2 minerals with the same composition be so different? What’s the point here? “Internal Arrangement of Atoms” controls most physical properties! MINERAL PROPERTIES FOR IDENTIFICATION a. Color Least dependable property because some minerals have lots of different colors b. Luster Appearance of the mineral surface in reflected light, how the mineral shines Metallic – looks like a metal Non-Metallic c. Hardness • Resistance to being scratched • https://www.youtube.com/watch?v=b7ANc WQEUI8 Moh’s Hardness Scale softest hardest d. Streak • Powdered form of a mineral, more reliable than color e. Cleavage Tendency of minerals to split along repeated smooth, flat planes. Look for places where the mineral might have split along flat and sometimes shiny planes that usually reflect light well. Look for stairsteps, sheets, squares, cubes e. Fracture Mineral breaks has a jagged or lumpy, irregular appearance f. Crystal shape • Geometric pattern that a lone crystal of the mineral will have SPECIAL PROPERTIES Fluorescence – mineral glows under a black light Double refraction Magnetism – some minerals are attracted to a magnet Taste – DO NOT EVER TASTE A MINERAL Reaction to acids Calcite and Dolomite will bubble when Hydrochloric Acid All mineral properties are determined by • The internal arrangement of atoms ROCK Composed of one or more minerals Classified by 1. Origin – how they were formed 2. Mineral Content 3. Texture 3 Types • Igneous • Sedimentary • Metamorphic ESRT Page 6
