Presentation on theme: "The Stuff that Rocks are made of"— Presentation transcript:
1The Stuff that Rocks are made of MineralsThe Stuff that Rocks are made ofPowerPoint Notes created by S. KoziolDate : 9/1/2013 Revised : ?/?/??
2Objectives What is a mineral? Define a mineral. Describe how minerals form.Identify the most common elements in Earth’s crust.PotashLiroconiteGoldSphalerite
3MineralsMinerals always exist in a solid(1) form.Salt
4Minerals (continued)A naturally occurring(2) substance is one that is made by natural processes. Thus, a substance developed in a lab, such as a synthetic diamond, cannot be considered a mineral. An inorganic substance is one that is not alive nor has ever been alive. Therefore coal, formed by an organic process, is not a mineral.
5Minerals - composition Although a few minerals are composed of single elements, most are made from compounds.(Mg,Fe)2SiO4SiO2OlivineQuartzSolids with a specific chemical composition.(3)
6Mineral - crystalsCrystal – Solid in which the atoms are arranged in repeating patterns(4)
7Mineral – crystals (continued) A mineral can take the shape of one of the six major crystal systems.
8MagmaMagma - Molten material found beneath Earth’s crust.
9Minerals - formationMinerals can form when differences in density force magma upward into cooler layers of Earth’s interior.
10Minerals - magmaWhen compounds in cooling magma no longer move freely, they may interact chemically to form minerals.
11Minerals – formation (continued) Mineral crystals may begin to precipitate out of a solution that has become saturated.Always have a scale in science images
12Minerals – formation (continued) Minerals form from cooled magma and from elements in solutions.
13Earth’s Crust – abundant elements The most abundant elements in Earth’s crust are silicon and oxygen.
14SilicatesSilicate - Mineral that contains silicon and oxygen. These make up the most common mineral group.SilicatesSub-classification based on tetrahedral structureNon-SilicatesNatives elements – only one elementSulfides - with a sulfur; tellurium, arsenic, or seleniumOxides – O22-Halides - (fluorine, chlorine, iodine, and bromine) is the main anion.Carbonates – [CO3]2-Sulfates – [SO4]2-Phosphates – [PO4]3-
15Common MineralsThe most common minerals, feldspar and quartz, are silicates.
16Think about itIf you took random samples of minerals from several locations, which type of mineral would you likely have more of—oxides, silicates, or carbonates. Why? There likely would be more silicates than other types because 96 percent of the minerals in Earth’s crust are silicates.
17Known MineralsThere are at least 4,900 known minerals in Earth’s crust.
18OreMinerals that contains a useful substance that can be mined for profit.Peacock Ore - copperArgentite - silver
19Ore - continuedThe classification of a mineral as an ore may change once it has been mined.
20Ore - continuedOres near Earth’s surface generally are obtained from open-pit mines.“525 m deep, 1200 meters in diameter. The air zone within this mine is closed for helicopters - a few accidents occurred when they were “sucked in” by downward air flow…”
21GemValuable mineral prized for its rarity and beauty
22Remember there was a reason for taking those class notes . . . Quiz BreakRemember there was a reason for taking those class notes . . .Quiz Break
23Of Identifying minerals ObjectivesOf Identifying mineralsClassify minerals according to their physical and chemical properties.Identify different types of minerals.Discuss how minerals are used.PotashLiroconiteGoldSphalerite
24ID-ing MineralsMinerals can be identified based on their physical and chemical properties.PhysicalChemical
25ID-ing Minerals - luster Silver, gold, and copper have shiny surfaces and thus are said to have metallic luster. Luster is described as either metallic or nonmetallic.GoldSilverCopper
26ID-ing Minerals - streak A mineral’s streak rarely changes, but sometimes does not match its external color, even if it is weathered or its external color varies slightly.
27ID-ing Minerals – trace elements Trace elements in a mineral can affect the color or the value of mineral.
28ID-ing Minerals – luster & streak Luster is the way a mineral reflects light from its surface, while streak is the color of a mineral when it is broken up and powdered. Both are tests used to identify a mineral.
29ID-ing Minerals – specific gravity Geologists commonly use specific gravity as a measure of density for accurate identification of a mineral.
30ID-ing Minerals – density vs. specific gravity Density is the ratio of the mass of a substance divided by its volume. Specific gravity is the most common measure of density. It is the ratio of the weight of a substance to the weight of an equal volume of water.
31ID-ing Minerals - hardness Mohs scale is used to compare the hardness of minerals.Finger nail ~2.2Glass, steel knife ~ 5.5Streak plate 7
32ID-ing Minerals - cleavage Mica has perfect cleavage in one direction; it breaks in sheets.
33ID-ing Minerals - fracture When flint and opals break, they have a unique fracture with arclike patterns.
34ID-ing Minerals – cleavage & fracture Minerals with cleavage split easily and evenly along one or more planes, while minerals with fracture break unevenly along jagged edges. Both describe how minerals split due to their atomic arrangements.
35ID-ing Minerals – hardness & texture Hardness is a measure of how easily a mineral can be scratched, while texture describes how a mineral feels. Both are tests used to identify a mineral.
36ID-ing Minerals - inorganic A mineral, such as salt, is naturally occurring but inorganic, in contrast to sugar, which comes from plants.
37The most reliable way to identify a mineral is by using a combination of several tests. cleavage - Property of splitting along one or more flat planes evenly and easily fracture - Property of breaking with rough or jagged edges hardness - Measure of how easily a mineral can be scratched streak - Color of a mineral when it is broken up and powdered luster - The way a mineral reflects light from its surface
38Why do geologists usually use a combination of tests to identify a mineral? Some minerals have characteristics similar to other minerals. Therefore, more than one test may be necessary to accurately identify the minerals.
39ID-ing Minerals – specific gravity Chemical FormulaBreakage PatternGold19.3AuHacklyApatite5Ca5(PO4)3(F, OH, Cl)Uneven fracturePyrite5.2FeS2Garnet3.5–4.3(Mg, Fe, Ca) 3 (Al2Si3O12)Conchoidal fractureBeryl2.75Be3Al2Si6O18Corundum4Al2O3FractureIf the volume of the sample of beryl equals the volume of the sample of gold, how many times greater is the mass of the gold sample than the mass of the beryl sample?SG 19.3 ÷ 2.75 = 7.02 times greater
40ID-ing Minerals - Hardness ColorHardnessGoldMetallic gold2.5–3ApatiteBlue, green5PyriteMetallic pale brass, gold6–6.5GarnetRed, deep red, brown6.5–7.5BerylBluish green, green7.5–8CorundumRed, deep red9
41ID-ing Minerals - Hardness ColorHardnessGoldMetallic gold2.5–3ApatiteBlue, green5PyriteMetallic pale brass, gold6–6.5GarnetRed, deep red, brown6.5–7.5BerylBluish green, green7.5–8CorundumRed, deep red9Which mineral can scratch at least one of the green stones?Which mineral can scratch neither green stone?Which mineral can scratch at least one of the red stones?Which mineral can scratch neither red stone?Which mineral can scratch only one of the green stones?pyritegoldberylapatitegarnet
42Remember there was a reason for taking those class notes . . . Quiz Break 2Remember there was a reason for taking those class notes . . .Quiz Break