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Rocks and Minerals

This article provides an overview of rocks and minerals, including their characteristics, formation processes, and methods of identification based on physical and chemical properties.

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Rocks and Minerals

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  1. Rocks and Minerals I. Minerals A. A mineral is 1. naturally occurring 2. inorganic 3. solid 4. definite chemical composition 5. a crystal structure • 1. naturally occurring: a. minerals – quartz, pyrite b. not minerals – cement, steel 2. Inorganic: Not formed from living things or the remains of living things. Coal plants a._______ is NOT a mineral because it comes from __________ Amber Tree sap b. ______ is NOT a mineral because it comes from ___________ Pearls oysters c. ______ are NOT minerals because they come from ___________ 1

  2. 3. Definite chemical composition 1 sodium 1 chlorine Halite NaCl Sodium Chloride SiO2 1 silicon 2 oxygen Silicon Dioxide Quartz Pyrite FeS2 1 iron 2 sulfur Iron sulfide Iron Oxide Hematite Fe2O3 2 iron 3 oxygen Fe3O4 Iron Oxide Magnetite 3 iron 4 oxygen CaCO3 1 calcium, 1 carbon 3 oxygen Calcite Calcium Carbonate Graphite C Carbon 1 carbon Diamond Carbon C 1 carbon Sulfur Sulfur S 1 sulfur 1

  3. Solids – have a definite___________________and a • definite _________________ Size / volume Shape Oil liquid _________ is NOT a mineral because it is a _________ 5. Crystal structure: Halite Atoms are arranged in repeating patterns. Characteristic geometry of its internal structure of atoms More crystal pictures 2

  4. B. Formation of minerals - 1. Form from cooling lava or magma 2. When water evaporates, dissolved minerals remain behind (when a solution is saturated with minerals, the minerals will settle out of the solution “precipitates”) • Identifying minerals – Minerals can be identified by their ___________ and __________ properties physical chemical A. Physical properties 1. Color • Some minerals have only one color: • (1) Malachite - ____________ • (2) Sulfur - ____________ green yellow b. Other minerals have many colors: (1) Quartz - _________________________________ _______________________________________ (2) Hematite - ________________________________ Clear, pink (rose), purple (amethyst) white (milky), grey/brown (smoky), etc. Black, grey, reddish brown, dark red 2

  5. c. Color can vary as the result of: (1) Natural coloring agents - impurities (2) Weathering – exposure to the environment (air, temperature changes, pollution) 2. Streak - the color of the powder when a mineral is rubbed on a streak plate • Hematite – colors: Black • grey • reddish brown dark red Streak: Reddish brown b. Quartz – colors: colorless grey white variety of colors Streak: White / colorless 3

  6. 3. Luster - the way a mineral shines or reflects light from its surface a. Metallicshines or reflectslight like the surface of a polished metal Examples: galena, pyrite, graphite, magnetite b. Nonmetallic– does not reflectlight like the surface of a polished metal (1) pearly - mica (2) glassy - quartz (3) dull, earthy - bauxite (4) waxy - talc (5) brilliant - diamond 4. Hardness - a measure of how easily a mineral can be scratched. a. Softest mineral - talc b. Hardest mineral - diamond 4

  7. c. Mohs scale of hardness Hardness of common objects Talc fingernail Gypsum copper Calcite Fluorite Iron nail Apatite glass Feldspar Quartz Steel file Topaz Streak plate Corundum Diamond 4

  8. 2.5 ? ? 5.5 ? 3.5 ? 4.5 5 ? 2 ? ? 8 3 ? Yes No Yes Yes 4 (2) (a) Will the mineral fluorite, Hardness be scratched by: _____ Yes a piece of glass?_______ No your fingernail?_______ Yes an iron nail?_______ 5

  9. 7 (b) Will the mineral quartz, Hardness be scratched by: _____ No a piece of glass?_______ No A copper penny?_______ No A steel file?_______ e. What determines hardness? Mineral’s internal structure The strength of the bonds between the atoms 5. Cleavage and fracture a. Cleavage - When a mineral splits along smooth, flat surfaces 5

  10. (1) Examples of cleavage: (a) The mineral mica cleaves in one ________ direction(s) (b) The mineral galena cleaves in three ________ direction(s) (2) What determines cleavage: Mineral’s internal structure The strength of the bonds between the atoms (3) Cleavage should not be confused with crystal shape. Cleavage is a property of the way a mineral _______, while crystal shape is a property of the way a mineral ________. When minerals have plenty of space to grow, they form ____________ breaks grows crystals 5

  11. When a mineral breaks unevenly into curved Or irregular pieces with rough & jagged surfaces b. Fracture - (1) Examples of minerals that show fracture Sulfur, bauxite, hematite, quartz • Density or Heft – due to the kinds of atoms a mineral contains and how closely packed the atoms are, different mineral samples of the same size have different densities and feel heaver or 8 lighter when lifted (or measured). A Piece of gold has ____ times as much mass as a piece of halite that is the same size. B. Chemical Properties calcite ___________ reacts with hydrochloric acid. It forms bubbles of carbon dioxide gas Calcite plus hydrochloric acid yields calcium chloride, water, & carbon dioxide CaCO3 + 2HCl CaCl2 + H2O + CO2 6

  12. C. Special Properties Magnetite Lodestone, a form of the mineral _________, is naturally _____________ Magnetic Calcite Iceland spar, a form of the mineral _________, produces ________________ double refraction pitchblende __________ is an example of a mineral that is ____________ radioactive 7

  13. III. Uses of minerals • A. Ore - a mineral that contains metals and nonmetals that can be mined and removed in usable amounts for a profit 1. Metals – elements that have shiny surfaces and are electricity Able to conduct __________ and ____________ heat Metal Mineral(s) Use Hematite Fe2O3 1. Iron Magnetite Fe3O4 8

  14. Metal Mineral(s) Use 2. Aluminum Bauxite Al(OH)3 AlO(OH) 3. Copper Chalcopyrite CuFeS2 Malachite Cu2CO3(OH)2 4. Lead Galena PbS 8

  15. Metal Mineral(s) Use 5. Silver Argentite AgS2 6. Gold Au 7. Mercury Cinnabar HgS 9

  16. Alloy b. ______ - a mixture of two or more metals or a mixture of metals and nonmetals bronze 1. Tin + copper _____________ brass 2. copper + zinc _____________ steel 3. iron + chromium + limestone _____________ pewter 4. lead + tin _____________ 2. Nonmetals – elements that have dull surfaces and are heat electricity Poor conductors of _________ and _____________ 9

  17. Mineral(s) Use table salt a. Halite NaCl b. Gypsum CaSO4.2H20 wallboard c. Sulfur S matches d. Talc MgSi4O10(OH)2 powder pencil lead e. Graphite C f. Kaolinite Al2Si2O5(OH)4 bricks cement g. Calcite CaCO3 9

  18. B. Gems – minerals that have the following desirable qualities: color, luster, Hardness, clarity, durability, rarity, 1. precious stones - diamonds, rubies, sapphires, emeralds amethyst, garnet, topaz 2. semiprecious stones - 3. gems that are not minerals - pearls, amber 10

  19. Important but not in the notepacket Did you write any of this down? S 10b I M

  20. Petrology _____________ The branch of science that studies rocks I. Classification of rocks classified • Rocks are ___________ on the basis of their Formation/origin __________________________ B. The three groups of rocks are: Sedimentary 1. _________________________ Igneous 2. __________________________ Metamorphic 3. __________________________ II. Rocks in relation to minerals minerals • Many kinds of rocks are composed of ___________ mica feldspar quartz 11

  21. monomineralic B. Some rocks are __________________ composed of only one mineral (limestone calcite) ___________________________________________________________ polymineralic C. Most rocks are __________________ composed of Two or more minerals (granite) ___________________________________________________________ D. LETTERS: WORDS::MINERALS: ROCKS 3,000 8 E. There are almost _______ types of minerals but only ____ 90 of these minerals make up ____% of the rocks of earth’s crust. Pyroxene 11% Quartz 12% Hornblende/amphibole 5% Biotite mica 5% Potassium feldspar 12% Clay minerals 4.6% Olivine 3% Plagioclase Feldspar 38% Other 8.4% 11

  22. III. Sedimentary Rocks A. Rocks that usually form in layers from the accumulation of sediments, organic matter, or chemical precipitates. 1. Most sedimentary rocks are made up of solid sediments that have been weathered from other rocks. The weathered sediments are then eroded (transported) by water , wind, and moving ice. Eventually the eroded sediments are deposited at new locations either in water or on land. Most sedimentary rocks form in layers underwater in lakes, seas, or oceans. 2. From sediments to rocks TIME Layers of sediment deposit and accumulate Pressure/weight squeezes lower layers Sediment compacted Into rock 12

  23. B. Types of Sedimentary Rocks. Clastic Form from rock particles/sediments that are _______ - _____________________________________ Pressed and cemented together _________________________________________ Compaction pressed by weight of overlying rock a. ___________ - ____________________________ Cementation glued by natural cements in water(calcite) b. ___________ - ____________________________ Individual particles of rock - sediment pressure Natural cements Dissolved in water After deposition compaction cementation 12

  24. c. Boulders Cobbles Pebbles 25.6 conglomerate 6.4 .2 Sandstone Sand .006 Siltstone Silt .0004 Shale Clay S 13

  25. Chemical Form from dissolved minerals in water 2. _________ - ______________________________ That settle-out / precipitate. Dissolved minerals _________________________________________ left behind when water evaporates _________________________________________ _________________________________________ Calcite Limestone Minerals dissolved in water precipitate out and forms as crystals on the sea floor Includes evaporites Rock Salt Halite Rock Gypsum Gypsum Dolomite Dolostone S 13

  26. Organic form from the accumulation of plant 3. ________- _________________________________ & animal matter that undergoes a transformation _________________________________________ Into rock. _________________________________________ Limestone Coal S 14 I M

  27. Formation of Coal Time Bituminous Lignite Peat Anthracite Soft Coal Brown Coal Hard Coal S 14 I M

  28. S I M

  29. C. Important characteristics of sedimentary rocks 1. they are composed of rock fragments or organic particles a. some have a range of particle or sediment size Conglomerate b. others consist mainly of one size of sediments – due to sorting during deposition sandstone S 15 I M

  30. 2. Some are organic – they form from plant or animal remains ______________ Fossils Fossil limestone 3. ____________________________ Form in layers called strata (or beds) Shale S 15 I M

  31. IV. Igneous Rocks A. Form from the cooling and solidification (crystallization) of molten lava and magma cools 1. When molten (liquid) lava or magma ________ and ___________ , crystals of different minerals form the rock solidifies a. The rock contains a crystalline structure of intergrown crystals of different _________ , _________, and ______________ sizes shapes composition S 16 I M

  32. B. Types of Igneous Rocks. Extrusive/Volcanic 1. _________________ - _________________________________ Forms from the fast Cooling of lava on or near the earth’s surface. Fast cooling _________________________________ Does not allow Time for crystals to grow. _________________________________ Rocks have Small or no crystals _________________________________ therefore a smooth / fine texture. _________________________________ S 16 I M

  33. Intrusive / Plutonic 2. _________________ - _________________________________ cooling of magma forms from the slow _________________________________ within the earth. Slow cooling allows time For large crystals to grow. _________________________________ Rocks have large crystals – therefore a _________________________________ Coarse / rough texture. _________________________________ S 16 I M

  34. Extrusive Lava Intrusive Magma S 17 I M

  35. 4 Environment of formation Very Fast Fast Slow Non- crystalline Less than 1 mm 1 mm or larger Glassy Fine Coarse Granite Gabbro Basalt Rhyolite Obsidian S 17 I M

  36. rate of crystal size 5. Relationship between ____________ and ________ ______ (the environment effects the cooling rate cooling As rate of cooling increases, crystal size decreases. a. __________________________________________ c. b. very fast No _______ cooling _______ crystals Crystal size fast small _______ cooling _______ crystals slow _______ cooling Rate of cooling large _______ crystals S 18 I M

  37. V. Metamorphic Rocks A. Form from other pre-existing rock (sed., ig., or meta.) That have been changed. B. Pressure Metamorphic rock Heat S 18 I M

  38. C. Conditions that cause rocks to undergo metamorphism include: pressure heat 1. ________ 2. ____________ chemical activity 3. ___________________ Such conditions are often associated with deep burial and pressure that result from mountain formation. Therefore, metamorphic rocks are often found in mountainous regions where weathering and erosion have exposed this rock that was once deeply buried. Under conditions of high temperature and high pressure, many metamorphic rocks form by the process of ________________. This is the growth of NEW mineral crystals from the sediments of a __________________ rock or the growth of NEW mineral crystals from the crystals of an ______________ or ___________________ rock. Recrystallization occurs without true melting. recrystallization sedimentary igneous metamorphic S 18 I M

  39. D. Changes in a Rock Caused by Metamorphism: Increased density 1. ___________________ 2. ___________________ Chemical change / new minerals Banding - Is a layered 3. _____________ arrangement of firmly joined crystals of minerals; the minerals are aligned in bands or layers. These bands are formed when rock is subjected to extreme pressure and temperature. Usually the greater the pressure and temperature, the thicker the bands. Distorted structure 4. ______________ - Is the curving and folding of the bands. These distortions of once horizontal bands are caused by great environmental pressure exerted on the rock from different directions S 19 I M

  40. E. Types of Metamorphic Rocks: Have mineral crystals arranged foliated 1. _________ - __________________________________ In parallel layers or “bands” __________________________________ Unfoliated Do NOT have minerals crystals 2. ___________ - ________________________________ In bands – do not break in layers / sheets __________________________________ S 20 I M

  41. Slate Shale Sed. Foliated Meta. Schist Slate Gneiss Granite Ig. Marble Limestone Sed. Unfoliated Quartzite Sandstone Sed. Anthracite coal Bituminous coal Sed. S 20 I M

  42. V. THE ROCK CYCLE Sedimentary rock Igneous rock Metamorphic rock S 20 I M

  43. Igneous Sedimentary clastic intrusive foliated unfoliated organic pumice marble schist quartzite gabbro rhyolite obsidian limestone shale granite slate limestone chalk siltstone gneiss Anthracite coal sandstone conglomerate basalt S 21 I M

  44. Famous Rocks Layers of Sedimentary Rocks (The Grand Canyon) Stonehenge “the White House” Limestone Pyramids Sandstone S 22 I M

  45. David Michelangelo’s Statue of (Marble) Gabbro “black granite” Vietnam war memorial granite Marble S 23 I M

  46. S I M

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