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Minerals Matter Matter is anything that has volume and mass Solid- definite shape and volume Liquid- only definite volume Gas- neither definite shape or volume Matter is made of… Element- cannot be broken down into simpler substance by chemical or physical means Periodic Table Elements are visually represented on the Periodic Table Symbol- letter(s) representing name of element Atomic number- above symbol (# of protons) Elements are made of… Atom- the smallest particle of matter that contains the characteristics of an element Atomic mass- protons AND neutrons Atomic #- number of protons # of protons = # of electrons (but ONLY protons are in nucleus, electrons orbit around the nucleus) Atoms of the same element ALWAYS have the same # of protons Atom model Isotope Atoms that have the same # of protons, but different numbers of neutrons Therefore, the mass number is different FYI- all atoms have the same atomic # BUT may have multiple isotopes (each with different mass #s) Isotopes…which element? http://images.encarta.msn.com/xrefmedia/aencmed/targets/illus/ilt/T046738A.gif Bonding of Atoms Bonding- atoms combine to form compounds- they either gain, lose or share electrons Compound- substance that consists of two or more elements that are chemically combined in specific proportions Minerals All minerals must meet these 5 criteria: 1. 2. 3. Naturally occurring- formed by natural geologic processes Solid- definite volume and shape Orderly crystalline structureatoms or ions are arranged in an orderly & repetitive manner Definite chemical compositionchemical compound made of 2 or more elements 5. Inorganic- not made of living or previously living compounds 4. How Minerals Form Crystallize from magma- as magma cools, elements combine Precipitation- water evaporates, or changes temperature, minerals are left behind Recrystallization- Changes in pressure & temperature, or atoms are rearranged creating new minerals Hydrothermal solutions- hot solutions chemically change minerals into new minerals Mineral Groups Common minerals are grouped based on composition Silicates- (most common) silicon (Si) & oxygen (O) Examples- quartz, olivine, augite, hornblende, mica, feldspars Carbonates- (2nd most common group) carbon (C), O & one or more other elements (usually a metal) Examples- calcite, dolomite Oxides- O & 1 or more elements (usually metals) Examples- rutile (titanium oxide), corundum (aluminum oxide), hematite (iron oxide) Sulfates sulfur (S) & Sulfides- contain Examples- anhydrite, gypsum, galena, sphalerite, pyrite Halides- halogen ion (from Group 7A on periodic table) Examples- (CaF2) halite (NaCl), flourite Native elements- exist in relatively pure form Examples: Gold (Au) Silver (Ag) Copper (Cu) Sulfur (S) Diamond and Graphite (C) Properties for Identification Color- not often reliable; small amounts of different elements give the same mineral different colors http://www.ayresdigitaldoodlings.com/images/WS%20Quartz%20Crystals.jpg Hardness- measure of the resistance of a mineral to being scratched Can be found by rubbing the mineral against another mineral (or object) of known hardness Mohs Hardness Scale- minerals are arranged on a scale from 10 (hardest) to 1 (softest) Streak- color of mineral in its powdered form Obtained by rubbing mineral across streak plate (unglazed porcelain tile) Color of mineral may vary, but streak does not Metallic minerals- dense, dark streak Luster- how light is reflected from the surface of a mineral Metallic- appearance of a metal Vitreous- glassy (like quartz) Submetallic- somewhat metallic Adamantine- diamond Pearly, silky, earthy Crystal form- visible expression of mineral’s internal arrangement of atoms http://www.thaigem.com/images/tg/images/buyer/mineral_crystal.jpg Cleavage- tendency of a mineral to cleave, or break, along flat, even surfaces Fracture- minerals that do not show cleavage when broken; uneven breakage Density- ratio of an object’s mass to volume (a specific mineral will always have the same density) Distinctive properties: Feel Smell Magnetic Transparent Chemically reactive