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Minerals

Minerals. Natural Solid Inorganic Definite chemical composition Crystal structure due to internal arrangement of atoms. http://www.minerals.net/gemstone/index.htm. http://www.mii.org/www.mii.org. General Facts about Minerals. Between 2 - 3,000 have been identified

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Minerals

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  1. Minerals • Natural • Solid • Inorganic • Definite chemical composition • Crystal structure due to internal arrangement of atoms http://www.minerals.net/gemstone/index.htm

  2. http://www.mii.org/www.mii.org

  3. General Facts about Minerals • Between 2 - 3,000 have been identified • A few are “native elements” -- made of only one element, such as sulfur, gold. copper, and graphite (carbon) • Most are compounds, especially the silicate group (Si, O). • Other important groups are oxides, carbonates, and sulfides.

  4. Quartz Feldspar (group) Muscovite (white mica) Biotite (black mica) Calcite Pyroxene Olivine Amphibole (group) Magnetite, limonite, and other iron oxides Pyrite Less than a dozen are common in most rocks

  5. Common uses include: • Aluminum--packaging, transport, building • Beryllium--gemstones, fluorescent lights • Copper--electric cables, wires, switches • Feldspar--glass and ceramics • Iron--buildings, automobiles, magnets • Calcite--toothpaste, construction • http://www.mii.org/commonminerals.php

  6. hardness crystal shape (form) luster color streak cleavage/fracture density (specific gravity) special properties --reaction to acid --fluorescence --salty taste --magnetism Minerals are identified by their key characteristics

  7. 1. Mineral Hardness • Ability to scratch another mineral • Mohs scale from 1 (talc) to 10 (diamond) • Quartz (most common mineral and most dust particles) is 7 http://mineral.galleries.com/minerals/elements/diamond/diamond.htm

  8. 2. Crystal Shape (Form) • External structure due to internal arrangement of the atoms • Six basic groups of shapes, with about three dozen variations http://www.minerals.net/mineral/carbonat/aragonit/aragoni1.htm

  9. 3. Luster • Describes how light reflects off the surface • Main categories are “metallic” and “non-metallic” • Non-metallic includes “dull,” glassy,” waxy,” “pearly,” and others http://www.minerals.net/mineral/sulfides/pyrite/pyrite2.htm http://www.minerals.net/mineral/sulfides/pyrite/pyrite2.htm

  10. 4. Color • results from ability to absorb some wavelengths and reflect others • some minerals have characteristics colors • others vary due to chemical differences or impurities (atoms mixed inside the main elements) http://www.minerals.net/mineral/carbonat/calcite/images/4assortd.htm

  11. 5. Streak • Color of the powder when rubbed on a “streak plate” (unglazed porcelain) • May be same as hand-specimen or different • Some paint is based on powdered minerals (streaks). http://www.minerals.net/mineral/oxides/hematite/hematit6.htm

  12. 6. Mineral cleavage/fracture • Some minerals split along flat surfaces when struck hard--this is called mineral cleavage • Other minerals break unevenly along rough or curved surfaces--this is called fracture • A few minerals have both cleavage and fracture

  13. 7. Density (Specific Gravity) • All minerals have density (mass / volume), but some are very dense • Examples include galena, magnetite, and gold • Specific Gravity is the density of the mineral compared with density of water http://www.minerals.net/mineral/elements/gold/gold1.htm

  14. Carbonates react with dilute HCl and other acids by fizzing or bubbling (releasing CO2 gas) Special Characteristics--1. the “Acid Test”

  15. Special Characteristics-- 2. Fluorescence • Some minerals will glow when placed under short-wave or long-wave ultraviolet rays • Franklin and Ogdensburg NJ are famous for their fluorescent minerals http://www.sterlinghill.org/Tour%20information.htm

  16. Special Characteristics--3. Salty Taste • DO NOT TASTE MOST MINERALS! • Halite is the exception--it will taste salty http://mineral.galleries.com/scripts/item.exe?LIST+Minerals+Halides+Halite

  17. Special Characteristics--4. Magnetism • Many iron minerals will produce an invisible magnetic force field • “Lodestone” was used by Vikings more than 1,000 years ago as compasses http://www.minerals.net/mineral/oxides/magnetit/magneti4.htm

  18. Mineral Identification Key • I. Mineral has a colored streak • A. Mineral has a black or grayish streak. • B. Mineral leaves a brown or reddish-brown streak. • C. Mineral leaves either a blue or a green streak. • II. Mineral does not leave a colored mark on streak plate, but leaves a white streak or scratches the streak plate. • A. Mineral will scratch glass • B. Mineral will not scratch glass but will scratch a penny. • C. Mineral will not scratch a penny, and cannot be scratched by your fingernail. • D. Mineral can be scratched by your fingernail.

  19. Mineral Identification Key

  20. Mineral has a colored streak.A. Mineral has a black or gray streak. • 1. Has a metallic gold appearance. It leaves a black Streak.= Pyrite • 2.Leaves a “lead gray” streak, and has a bright silver metallic luster. It’s heavy.= Galena

  21. I. A. Mineral has a black or grayish streak. • 3. Will write on paper (easily), and feels greasy. = Graphite • 4. Is “magnetic” = Magnetite

  22. I. B. Mineral leaves a brown or reddish-brown streak. • 1. Has brown circles on it’s surface. = Bauxite • 2. Has a bumpy surface. = Hematite

  23. I. C. Mineral leaves either a blue or a green streak. • 1. Green streak. = Malachite • (Often appears with Azurite.) • 2. Blue streak.=Azurite • (Often appears with Malachite)

  24. Mineral Identification Key

  25. II. No colored mark on the streak plate, but leaves a white streak or scratches streakplate. II. A. Will scratch glass. Hardness 6-10 • 1. Clear or translucent. Has a hardness of 7.= Quartz • If Pink = Rose Quartz. • If Dark = Smoky Quartz.

  26. II. A. Mineral will scratch glassHardness: 6-10 • 5. Is orange and white in color. It has a hardness of 6. Distinct 90 ̊ cleavage. = Feldspar • 3. Mineral is reddish-purple in color and has a hardness of 9. = Corondum

  27. II. B. Mineral will not scratch glass, but will scratch a penny. Hardness: 4-5 • 1. Mineral is light green in color and has a hardness of 5. = Apatite • 5. Translucent and writing appears double when looking through it. = Calcite

  28. II. B. Mineral will not scratch glass, but will scratch a penny. • 4. Transparent to translucent. Mineral varies in color. It is often purple. Often shows good cleavage. = Fluorite

  29. II. C. Mineral will not scratch a penny, and cannot be scratched by your fingernail. Hardness: 2-3 1. Mineral has cubic cleavage and tastes salty. = Halite 2.Is in think flat sheets and peels off in layers. In Mica Family. -Dark Mica=Biotite -Light Mica=Muscovite

  30. II. D. Mineral can be scratched by your fingernail. Hardness: 1-2 • 1. Mineral feels soapy and has a hardness of one. = Talc • 2. Transparent or translucent and has good cleavage. Mineral has silky luster and hardness of two. = Gypsum

  31. Useful Web Sites • www.mii.org • www.mineral.galleries.com/minerals • www.mineral.net • www.usgs.gov • http://geology.about.com/library/bl/images/blmineralindex.htm

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