Presentation on theme: "Minerals The Stuff that Rocks are made of PowerPoint Notes created by S. Koziol Date : 9/1/2013 Revised : ?/?/??"— Presentation transcript:
Minerals The Stuff that Rocks are made of PowerPoint Notes created by S. Koziol Date : 9/1/2013 Revised : ?/?/??
Objectives What is a mineral? Define a mineral. Describe how minerals form. Identify the most common elements in Earths crust. Liroconite Potash Sphalerite Gold
Minerals Minerals always exist in a solid (1) form. Salt
Minerals (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.
Minerals - composition Although a few minerals are composed of single elements, most are made from compounds. Quartz SiO 2 Olivine (Mg,Fe) 2 SiO 4 Solids with a specific chemical composition. (3)
Mineral - crystals Crystal – Solid in which the atoms are arranged in repeating patterns (4)
Mineral – crystals (continued) A mineral can take the shape of one of the six major crystal systems.
Magma Magma - Molten material found beneath Earths crust.
Minerals - formation Minerals can form when differences in density force magma upward into cooler layers of Earths interior.
Minerals - magma When compounds in cooling magma no longer move freely, they may interact chemically to form minerals.
Minerals – formation (continued) Mineral crystals may begin to precipitate out of a solution that has become saturated. Always have a scale in science images
Minerals – formation (continued) Minerals form from cooled magma and from elements in solutions.
Earths Crust – abundant elements The most abundant elements in Earths crust are silicon and oxygen.
Silicates Silicate - Mineral that contains silicon and oxygen. These make up the most common mineral group. Silicates Sub-classification based on tetrahedral structure Non-Silicates Natives elements – only one element Sulfides - with a sulfur; tellurium, arsenic, or selenium Oxides – O 2 2- Halides - (fluorine, chlorine, iodine, and bromine) is the main anion. Carbonates – [CO 3 ] 2- Sulfates – [SO 4 ] 2- Phosphates – [PO 4 ] 3-
Common Minerals The most common minerals, feldspar and quartz, are silicates.
Think about it If you took random samples of minerals from several locations, which type of mineral would you likely have more ofoxides, silicates, or carbonates. Why? There likely would be more silicates than other types because 96 percent of the minerals in Earths crust are silicates.
Known Minerals There are at least 4,900 known minerals in Earths crust.
Ore Minerals that contains a useful substance that can be mined for profit. Peacock Ore - copper Argentite - silver
Ore - continued The classification of a mineral as an ore may change once it has been mined.
Ore - continued Ores near Earths 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…
Gem Valuable mineral prized for its rarity and beauty
Quiz Break Remember there was a reason for taking those class notes...
Objectives Of Identifying minerals Classify minerals according to their physical and chemical properties. Identify different types of minerals. Discuss how minerals are used. Liroconite Potash Sphalerite Gold
ID-ing Minerals Minerals can be identified based on their physical and chemical properties. PhysicalChemical
ID-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. Gold Silver Copper
ID-ing Minerals - streak A minerals streak rarely changes, but sometimes does not match its external color, even if it is weathered or its external color varies slightly.
ID-ing Minerals – trace elements Trace elements in a mineral can affect the color or the value of mineral.
ID-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.
ID-ing Minerals – specific gravity Geologists commonly use specific gravity as a measure of density for accurate identification of a mineral.
ID-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.
ID-ing Minerals - hardness Mohs scale is used to compare the hardness of minerals. Finger nail ~2.2 Glass, steel knife ~ 5.5 Streak plate 7
ID-ing Minerals - cleavage Mica has perfect cleavage in one direction; it breaks in sheets.
ID-ing Minerals - fracture When flint and opals break, they have a unique fracture with arclike patterns.
ID-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.
ID-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.
ID-ing Minerals - inorganic A mineral, such as salt, is naturally occurring but inorganic, in contrast to sugar, which comes from plants.
The 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
Why 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.
ID-ing Minerals – specific gravity MineralSpecific GravityChemical FormulaBreakage Pattern Gold19.3AuHackly Apatite5Ca 5 (PO 4 ) 3 (F, OH, Cl)Uneven fracture Pyrite5.2FeS 2 Uneven fracture Garnet3.5–4.3 (Mg, Fe, Ca) 3 (Al 2 Si 3 O 12 ) Conchoidal fracture Beryl2.75Be 3 Al 2 Si6O 18 Uneven fracture Corundum4Al 2 O 3 Fracture If 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
ID-ing Minerals - Hardness MineralColorHardness GoldMetallic gold2.5–3 ApatiteBlue, green5 PyriteMetallic pale brass, gold6–6.5 GarnetRed, deep red, brown6.5–7.5 BerylBluish green, green7.5–8 CorundumRed, deep red9
ID-ing Minerals - Hardness MineralColorHardness GoldMetallic gold2.5–3 ApatiteBlue, green5 PyriteMetallic pale brass, gold6–6.5 GarnetRed, deep red, brown6.5–7.5 BerylBluish green, green7.5–8 CorundumRed, deep red9 Which 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? pyrite gold beryl apatite garnet
Quiz Break 2 Remember there was a reason for taking those class notes...