Geology Minerals Test/Chapter Four – Flashcards
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The way in which a mineral breaks is called its
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cleavage
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Which of the following minerals could be scratched by all of the others
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gypsum
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Most crystals do not exhibit their internal structure by their outward shape because
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they didn't grow in a unconstrained environment
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How will a mineral break if all of its bonds are equal in strength preventing the mineral from breaking along any plane?
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irregular curved fracture
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What element makes up the most important group of minerals on Earth?
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Si
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Sulfates contain sulfur and
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oxygen
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Calcite is an important
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carbonate
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The Silicon-Oxygen tetrahedron is the basic building block of the silicate minerals. What atoms does it contain?
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one Si and 4 O
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The tetrahedron has an overall charge of
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-4
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independent tetrahedra
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olivine
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single chain
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pyroxenes
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double chains
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amphiboles
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sheets
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mica and clay
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framework
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quartz and feldspar
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Quartz (SiO2) is a silicate with one Si for every 2 O. It is
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silica
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Quartz
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hard mineral that breaks with conchoidal fracture
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Olivine
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a green mineral composed of iron and magnesium w independent tetrahedra
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Pyroxene
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a mafic single chained silicate w 90 degree cleavage planes
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muscovite
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a light aluminum silicate with a single cleavage plane
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amphibole
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a double chained mafic silicate w long skinny crystals
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plagioclase
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a felsic silicate which is either rich in Ca or in Na
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biotite
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a dark sheet silicate
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The word _______________ could either refer to a silicate mineral that forms microscopic sheets, or the word could refer to the smallest sized fragment, regardless of its mineral content
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clay
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pyrite
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FeS2; also known as fool's gold
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hematite
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an iron oxide w a red streak
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magnetite
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an iron oxide that is magnetic
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calcite
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calcium carbonate mineral that makes up limestone and shells
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halite
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NaCl
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galena
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dense metallic mineral that contains lead
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gypsum
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a chemical precipitate that is a hydrated (contains water) sulfate
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Rocks of the mantle and ocean crust have high iron and magnesium content, and are called
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mafic
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Where would you find the most diverse set of minerals?
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at the surface
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What mineral is common in the mantle?
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olivine
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What is the most abundant element in the crust?
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oxygen
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What will chlorine do in order to become more stable?
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gain an electron to become a negative ion
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Oxygen is in the VI column of the periodic table which means that it
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needs 2 more electrons to complete its outer shell
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The Van de Waals bonds in mica and clay are best described as
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intermolecular forces
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In calcite the bonds are
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covalent between C and O, but ionic with Ca
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What kind of bonds make a diamond such a hard mineral?
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covalent
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Why does salt dissolve in water?
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the polar water molecules attract the Na+ and the Cl- ions
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What happens when salt water evaporates?
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Na+ and Cl- form ionic bonds and precipitate
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Lakes rarely freeze solid because
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water is denser than ice
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What is the main ingredient in cement?
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calcite
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Kitty litter is made out of __________ because it absorbs liquids very well
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clay
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Which of the following minerals contains useful amounts of copper
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malachite
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Define what a mineral is and explain the difference between a rock and a mineral
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a mineral is a naturally occurring, solid, inorganic compound with a unique chemical composition and crystalline structure. a rock is a solid mass composed of multiple minerals or other organic compounds
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explain the difference between a clastic rock and a crystalline rock
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a clastic rock is composed of older rocks or previously existing solid matter. a crystalline rock is made up of minerals in crystalline structure
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explain the following properties of a mineral
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hardness-resistance to being scratched acid test-reaction to HCl (bubbles=effervesces) streak-color of a mineral's streak (not always the same as its color) magnetism-magnetite makes minerals magnetic specific gravity-mineral's density (classified as light, medium, and heavy) luster-metallic (medal looking) or non-metallic (vitreous-->glassy, silky, pearly, dull/earthy, resinous-->waxy) cleavage-the way in which a mineral breaks (shows atomic structure)-->number of panes and relative degrees crystal shape-the way in which a mineral forms
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define crystalline structure
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uniform atomic structure throughout the entire material
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explain cleavage in a mineral and be able to identify the number of cleavage planes of minerals
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-the way in which a mineral breaks (different than the way it forms) -cleavage planes, conchoidal fracture etc.
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summarize the following classes of minerals and the main chemical characteristic of each class and examples of each
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Silicates: contain S2- and O2- (esp. SiO2^4-) important metal ores, ex. galena: Pbs-->lead sulfide Carbonates: contain CO3^2-, ex. calcite: CaCO3 (most imp./common) Oxides: contain O^2- and another element, ex. magnetite: Fe3O4, hematite: Fe2O3 Halides: contain a halogen (F, Cl, Br, I, At), ex. halite: NaCl Sulfates: contain SO4^2-, ex. gypsum: CaSO42H20, calcium sulfate dihydrate Sulfides: contain S2- ex. galena: Pbs, sulfur: S2-, pyrite: FeS2-->iron sulfide
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sketch or explain a silica tetrahedron and how 2 tetrahedra can join
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SiO4^4- tetrahedrons connected by cations see diagram
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explain or sketch how silica tetrahedra link in different geometries to produce five silicate mineral groups
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-isolated tetrahedra (tetrahedra connected by cations) -single chains (tetrahedra share oxygens (covalent bonds) to create chains that are connected by cations (ionic bonds) -doubles chains (tetrahedra share oxygens (covalent bonds) to create double chains that are connected by (ionic bonds) cations) -sheet (tetrahedra share oxygens (covalent bonds) to create sheets that are connected by (ionic bonds) cations (muscovite-->biotite mica, muscovite mica, kaolinite) -framework (tetrahedrons share oxygens (covalent bonds) to create a solid structure (feldspar-->quartz)
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know at least one example of each silicate mineral group
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-isolated tetrahedra=olivine -single chains=pyroxenes (augite) -double chains=amphiboles-->hornblende -sheet=mica -framework=quartz
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list the four most abundant elements in the crust and in Earth as a whole, and explain why silicate minerals are so abundant in the crust and mantle
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1. oxygen 2. silicon 3. aluminum 4. iron -silicate minerals are abundant: when earth cooled dense materials sunk to the core light materials (silicates) moved outside to form crust
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explain the different types of bonds and how electrons cause each type
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-ionic=weak in minerals, transfer of electrons -covalent=stronger than ionic in minerals, transferring electrons -metallic=bonding within metals, stronger bonds, sharing of electrons among a lattice of cations -van der waals=weak
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describe how halite dissolves and crystallizes in water and be able to explain the "crystal tree"
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-Cl- is attractive to H+ and if the attraction is strong enough the Cl is pulled away from the Na+Na is attractive to O2- and if the attraction is strong enough the Na is pulled away from the Cl -crystal tree: once dissolved in water Na is surrounded by the negative side of the water molecule (O2-) Cl- is surrounded by the positive side of the water molecule (H+)
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Describe some uses of common minerals
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see around
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Describe some ways we use the physical properties of minerals
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see around
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describe the geologic environments in which some gemstones form
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see around
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Quartz
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SiO2-->silicate non-metallic glassy hard (7) conchoidal fracture forms hexagonal prism and pyramids uses: abrasive, glass, gemstones
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Olivine
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(Fe, Mg)2SiO4-->silicate non-metallic dull hard poor or absent cleavage pale or dark olive green to yellow, or brown heavy uses: gemstone (peridot), ore of magnesium
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Hornblende
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double chain silicate splintery long black crystals fibrous fracture light to pale grey streak uses: fire-resistant clothing
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Augite
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silicate green-black 2 cleavage planes (90 degree) brittle soft/hard (5.5-6) streak: light to pale grey uses: ore of lithium
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biotite mica
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aluminum silicate black (Fe, Mg) 1 perfect cleavage plane light sheety/smooth/flaky soft uses: rubber, tires, paint
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muscovite mica
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aluminum silicate 1 perfect cleavage plane gold sheety light soft uses: roof shingles, makeup, glitter
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plagioclase feldspar
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KAlSi3O8-->silicate non-metallic glassy white! hard parallel striations (scratches) 2 cleavage planes (90 degree) brittle uses: ceramics, glass, enamel, soap, false teeth, scouring powders
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potassium feldspar
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KAlSi3O8-->silicate pink! non metallic glassy hard lamellae (wavy lines) 2 cleavage planes (90 degree) uses: ceramics, enamel, soap, false teeth, sourcing powders
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Talc
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Mg3Si4O10(OH)2-->Silicate non-metallic pearly (feels soapy) microscopic cleavage (powdery/chalky) light very soft uses: talcum powder, facial makeup, paint, ceramics, sculptures
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Kaolinite (clay)
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sheet silicate (too small to see individual crystals) very soft non metallic dull excellant microscopic cleavage (feels chalky/powdery) uses: pottery, clay
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Gypsum
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CaSO4*2H2O-->sulfate non-metallic glassy 2-3 cleavage planes (2 excellant + 1 weak-->not at 90 degree--> can look like a rhombus) very soft transparent-translucent uses: plaster (heat up to remove water-->add water=plaster of paris)
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diamond
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C 111 cleavage planes (perfect in 4 directions) hard (10) non metallic glassy uses: jewelry, saw blades
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Magnetite
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Fe3O4-->iron oxide grey streak heavy magnetic metallic uses: ore of iron
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Hematite
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Fe2O3-->iron oxide red streak hard no cleavage rough/earthy metallic uses: important ore of iron, makeup (red), paint (red)
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Galena
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PbS-->sulfide silver soft 3 cleavage planes (90 degree) heavy metallic uses: ore of lead
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Sulfur
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S-->sulfide non-metallic dull yellow (streak and color) very soft light smells bad uses: sulfuric acid
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Graphite
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C metallic very soft 1 cleavage plane (very soft) silvery grey to black forms flakes, short hexagonal prisms, and earthy masses feels greasy uses: lubricant (as in graphite oil), pencil leads, fishing rods
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Calcite
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CaCO3-->Carbonate non-metallic opaque excellant cleavage planes (not 90 degree) rhombus HCl causes to effervesce double refraction
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Halite
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NaCl-->halide non-metallic very soft, 2 excellant cleavage in 3 directions (90 degree) uses: table salt
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Azurite
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copper carbonate non-metallic blue soft uses: ore of copper
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Malachite
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copper carbonate non metallic green soft uses: ore of copper
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Mineral Properties Lab...see
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see
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feldspar
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most common mineral
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rocks v mineral
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rock=mixture of minerals mineral=pure substance (definite chemical composition Ex. SiO2), solid, crystalline structure, naturally occurring
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ion
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charged atom which has gained/lost an electron
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isotope
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an atom with an unusual number of neutrons-->unusual mass
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Kinds of bonds
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ionic-bond btwn 2 oppositely charged ions covalent-bond btwn atoms that share electrons metallic-fast w electrons-->conduct van der waals-very weak bond
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important ions in minerals
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negative ions (anions-gained electrons) non metals ex. O-2, Cl- positive ions (most important in minerals) most are metals ex. Fe+2 *cations tend to move easily, replace each other
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graphite forms
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under greatest temperature -can be burned, when you burn something you oxidize it
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diamond forms
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under greatest pressure
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rules for building a mineral
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every atom of one element has 2 critical characteristics: characteristic radius about 0.2-2.5X10^-10 characteristic valence (ionic charge) total charge of the unit cell (building block) must be zero; otherwise powerful electric field forces would explode structure positive ions touch negative ions (usually O-2) but not each other number of anions (oxygens) around a cation is determined by the ratio of their radii bonding of a cation to anion is due to attraction or bond, either: ionic, covalent order created incrementally as crystal grows
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important non silicates
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carbon graphite diamond
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Carbonates
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CaCO3=calcite CaMg(CO3)2=dolomite
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Oxides
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combined with oxygen magnetite=Fe3O4, magnetic Hematite=Fe2O3, red/rust both are important ores of iron/steel
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Chloride
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NaCl common mineral formed by the evaporation of seawater -salt/halite -crystalline cubic structure 3 cleavage planes at right angles
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sulfate
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SO4-2 gypsum calcium sulfate dihydrate CaSO42H2O
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sulfides
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pyrite galena sphalerite -important metal ores
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sheet silicate
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neg charge micas clay
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Hardness
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resistance to being scratched scratch test-->scratch 2 things-->whichever scratched the other is harder moh's scale of mineral hardness 1. talc 2. gypsum 3. calcite 4. fluorite 5. apatite 6. feldspar 7. quartz 8. topaz 9. corundum 10. diamond 2.5=fingernail 5.5=glass 6-6.5=steel file (ex. knife)
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Tenacity
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resistance to being broken or bent or deformed in any way brittle (ex diamond, glass) elastic (ex. ball, mica)-bounds back into shape once you've tried to deform it malleable (ex gold-->most malleable mineral)-bend it into whatever shape you want to fibrous (ex asbestos) sectile (ex can carve it with a knife) flexible (bendable but doesn't snap back into shape)
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Cleavage
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the way in which a mineral breaks-->shows atomic structure number of planes and relative degrees of planes help decipher element best way to figure out-->smash rock-->can't-->closely examine-->flash of light on cleavage crystalline pattern-easy to see how atoms separate to produce cleavage with cubic 90 degree angles-->break along weak bonds galena + fluorite-straight cut lines are natural common salt (halite) very good cleavage in 3 drxns at 90 degree angles feldspar blocky cleavage (2 drxns) some minerals so small can't see cleavage planes talc (soap), feels soapy and smooth bc the minerals break at cleavage planes fluorite=cleavage octahedron (4 planes)-->double pyramid-->both side's cleavage planes at same angle are the same plane
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Fracture
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obsidian (not a mineral) + quartz-conchoidal fracture-->breaks along a curved line
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streak
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the color of a mineral's powder (not its color) streak plate=ceramic tile hematite=red streak sphalerite=ore of zinc, yellow streak gold-gold streak, fools gold-grey streak
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luster
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not obvious if rock has weathered -metallic shiny in a medal kind of way-->can be silver or gold -silver -stibnite -galena -marcasite -pyrite -non metallic glassy silky pearly dull resinous graphite
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color
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the worst way to identify a rock calcite=has various colors quartz=add tiny bits of other things get tons of other colors indicative color minerals w single distinct colors= turquoise sulfur rhodochrosite=pink malachite azurite
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specific gravity
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classified as light, medium, heavy gold very heavy
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taste
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halite is salty
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magnetism
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magnetite is lodestone (so magnetic, its called a magnet)
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diaphaneity
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how light goes thru a mineral -transparent -translucent -opaque
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double refraction
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see double thru it iceland spar calcite
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chemical properties
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reaction to dilute HCl calcite reacts-->bubbles CO2
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radioactivity
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geiger counter used to find uranium ore is radioactive
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fluorescence
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some minerals glow under UV light
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