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Rocks and Minerals

Rocks and Minerals. Lecture Part I: Minerals. Five Properties of Minerals. Crystal Structure. Naturally occurring. Solid. Definite Chemical Composition. Definite volume and shape. Formed by processes in natural world. mineral. Inorganic. Did not come from something living.

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Rocks and Minerals

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  1. Rocks and Minerals Lecture Part I: Minerals

  2. Five Properties of Minerals Crystal Structure Naturally occurring Solid Definite Chemical Composition Definite volume and shape Formed by processes in natural world mineral Inorganic Did not come from something living Repeating pattern Always contains the same elements

  3. Scientists use 8 different properties to identify minerals. Over 4,000 minerals exist!

  4. color • streak • luster • density • hardness • Crystal type • cleavage or fracture • special properties How do we identify minerals?

  5. Which one is the mineral, gold? 1. Color - easily observed but many minerals have the same color. Pyrite Gold Chalcopyrite

  6. Try it: hematite #19 & galena #14 2. Streak – the color of a mineral’s powder.

  7. Metallic Glassy Waxy, Greasy 3. Luster – how light reflects on the surface of the mineral. Dull Silky Earthy

  8. The mass in a given space – how much “stuff” is in the mineral. The density does not change based on size. Density = Mass / Volume 4. Density

  9. Mohs Hardness Scale (1812) – ranks ten minerals from hard to soft. • A scratch test is used to determine hardness. 5. Hardness – one of the best clues to identify a mineral.

  10. 6. Crystal Systems – atoms in a mineral grow in a pattern.

  11. A mineral that splits evenly along flat surfaces. A mineral that does not split apart evenly. 7. Cleavage & Fracture mica talc

  12. Some minerals have fluorescence, magnetism, reactivity to acids, and optical properties. 8. Special Properties

  13. IN SUMMARY… • Minerals are INORGANIC and naturally occurring. • Minerals have a crystal structure with a definite chemical composition. • They are identified by their color, streak, luster, density, hardness, cleavage or fracture, and special properties.

  14. HOW MINERALS FORM

  15. What is the difference between a rock & a mineral? • What are the five characteristics of ALL minerals? • What are 8 properties used to identify minerals? • How do you calculate density? • What is the difference between cleavage & fracture? • What is the difference between color & streak? • What is the Mohs Hardness Scale? Pop Quiz

  16. Crystallization The process by which atoms are arranged to form a material with a crystal structure. geode

  17. crystallization of lava or magma, • crystallization of materials in solutions. Two Ways Minerals Form

  18. When these liquids cool to a solid state, they form crystals. Minerals From Magma & Lava

  19. Solution - A mixture in which one substance is dissolved in another. Minerals From Solutions

  20. When ancient seas slowly evaporated, minerals formed (halite, gypsum, calcite). Minerals Formed by Evaporation HALITE

  21. Elements that form minerals dissolve in hot water underground; when the solution cools, the elements crystallize as minerals. These iron-rich minerals formed at an undersea vent Minerals from Hot Water Solutions

  22. A narrow channel of a mineral that is different from the surrounding rock; usually pure metals. Pure Metal Veins

  23. Depends on the rate at which the magma/lava cools or the solution evaporates. The Size of Crystals

  24. Slow cooling leads to the formation of large crystals. Slow Cooling Crystals

  25. Magma closer to the surface loses heat energy much faster than magma deep below ground. • Rapid cooling leaves no time for large crystals. • Crystals are small. Rapid Cooling Crystals

  26. Minerals form from magma and lava when the hot magma cools inside the crust or the lava hardens on the surface. • Minerals form when elements and compounds are dissolved in water and they leave a solution which eventually crystallizes. • Minerals form when solutions evaporate (Example: halite from the ancient seas and gypsum) IN SUMMARY…

  27. Preview “minerals an their uses” • Mineral identification using samples. • Name of mineral • 3 words to DESCRIBE it. • Mineral poster – front side • Title: Your mineral • In the center draw/print/glue a picture of something that contains your mineral • 5 bubbles around the picture in the center that describe the PROPERTIES of that mineral • Minerals Lab Part I: DENSITY (review identification properties) • Analysis: explain the other ways to identify minerals. • Make crystals with kit • Make your own sugar crystals

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