OBJECTIVES: CH 4- MINERALS Identify characteristics and formations of minerals Differentiate Minerals by their groups and uses STANDARDS:
MINERAL: WHAT IS A MINERAL? A naturally occurring Inorganic Solid Specific chemical composition Definite crystalline structure.
CHARACTERISTICS OF MINERALS Naturally Occurring and Inorganic Minerals are formed by natural processes Magma or precipitates Minerals are not alive and were never alive at any part of their existence Solids with Specific Composition Minerals are ALL SOLIDS NO gas or liquid can be classified a mineral Each type of mineral has a unique chemical composition EX: few are formed from just one element (copper, silver, sulfur) Most are formed from compounds Definite Crystalline Structure Atoms are arranged in repeating patterns = crystals Table 4.1 on pg. 78 shows Common Crystal Structures
CRYSTAL STRUCTURES
MINERAL FORMATION Minerals From Magma Magma: molten material found beneath Earth s surface. Type and amount of compounds in the magma determine which minerals will form Cooling rate determines crystal size. Cools slowly = large crystal formation Cools quickly = small crystal formation Minerals from Solution Minerals form when solutions become saturated (unable to dissolve any more solute) If solution becomes supersaturated minerals precipitate (form) If liquid from a supersaturated solution evaporates what is left behind are elements/compounds that can form crystals ->minerals
MINERAL GROUPS SILICATES Minerals that contains silicon (Si) and Oxygen (O) and usually one or more other elements. Make up 96% of the minerals in Earth s crust Most common minerals Feldspar and quartz Mica CARBONATES Minerals composed of one or more metallic elements with the carbonate compound (CO 3 ) EXAMPLES: Calcite, dolomite, rhodochrosite Found in rocks such as limestone, coquina, and marble Some have distinct colorations
MINERAL GROUPS OXIDES Compounds of oxygen and metal EXAMPLES: Hematite (Fe 2 O 3 ) Magnetite (Fe 3 O 4 ) = common iron oxides Uraninite is a major source of uranium used to generate power OTHER MINERAL GROUPS Sulfides Sulfates Halides (salts) Native elements Copper, Silver
MINERAL IDENTIFICATION COLOR Color of the actual mineral LUSTER The way that a mineral reflects light from its surface categorized as metallic (shiny) silver, gold, copper, galena nonmetallic (dull, pearly, waxy or silky) calcite, gypsum, sulfur, quartz TEXTURE How a mineral feels to the touch Describe as smooth, rough, ragged, greasy, soapy or glassy STREAK The color of a mineral when it is broken up and powdered
HARDNESS MINERAL IDENTIFICATION A measure of how easily a mineral can be scratched Moh s scale of mineral hardness Softest 1 can be scratched by fingernail Hardest 10 diamond can be used to sharpen other metals and as a cutting tool See Pg. 86 Table 4-3
MINERAL IDENTIFICATION CLEAVAGE AND FRACTURE Cleavage: Ability of a mineral to break easily and evenly along one or more flat planes Fracture: ability of a mineral to break into pieces with arc-like, rough, or jagged edges. DENSITY AND SPECIFIC GRAVITY Density = Mass/volume minerals of the same size may feel quite heavier when they are lifted. Specific gravity: the ratio of the weight of a substance to the weight of an equal volume of water at 4 degrees C
ORES Mineral that contains a valuable substance that can be mined EXAMPLES: bauxite - contains Aluminum, hematite contains Iron MINERAL USES MINES Ores are found beneath the surface, must be remove d by underground mining Unwanted dirt and rock is known as waste material Waste material is expensive to remove and harmful to the environment
GEMS MINERAL USES Rare, precious, highly prized mineral that can be cut, polished, and used for jewelry EXAMPLES: Rubies Emeralds Diamonds Amethyst Sapphires