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Minerals, Composition and Structure

Minerals, Composition and Structure. What is a mineral?. Definition: Naturally Occurring Inorganic Orderly Crystal Structure Definite chemical composition. How do minerals form?. Four major processes Crystallization from magma Molten rock that cools and hardens into rock Precipitation

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Minerals, Composition and Structure

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  1. Minerals,Composition and Structure

  2. What is a mineral? • Definition: • Naturally Occurring • Inorganic • Orderly Crystal Structure • Definite chemical composition

  3. How do minerals form? • Four major processes • Crystallization from magma • Molten rock that cools and hardens into rock • Precipitation • Dissolved substances form minerals when water evaporates • Pressure and temperature • Changes in pressure and temperature cause atoms to rearrange forming new minerals • Hydrothermal Solutions • Hot mixture of dissolved substances that cause chemical reactions

  4. 6 Mineral Groups • Silicates • Carbonates • Oxides • Sulfates and Sulfides • Halides • Native elements

  5. Silicates • Contain Silica and Oxygen to form a tetrahedron SiO2

  6. Carbonates Contain carbon, oxygen, and one or more other metallic element CaCO3

  7. Oxides Contain oxygen and one or more other element Fe2O3

  8. Sulfates and Sulfides Contain the element sulfur ZnS

  9. Halides Contain halogen ion plus one or more other element

  10. Native elements Contain only one element S

  11. 6 Crystallographic Groups

  12. Do Now! • Observe the minerals on your table. Choose a specific feature of the minerals and group them based on that feature. • Answer the following questions: • How did you group your minerals? • Is there another feature you could use to group them together? • What feature did other groups choose?

  13. Mineral Identification • Every mineral can be identified through its unique characteristics. These characteristics are a result of their chemical composition and crystal structure as previously discussed.

  14. Crystal Form • Crystal form – visible expression of a mineral’s internal arrangement of atoms.

  15. Luster • Luster – how light reflects off the surface of a mineral • Metallic – have the appearance of metals, regardless of their color. • Nonmetallic – can be described by many adjectives like: glassy, vitreous, pearly, silky, and earthy.

  16. Streak • Streak – color of a mineral in its powdered form. Most useful with metallic luster samples • May be different from color in hand sample form

  17. Hardness • Hardness – measurement of a mineral’s resistance to being scratched. • Be specific if less than 5 • Say “greater than 5” if harder than nail Moh’s Hardness Scale

  18. Cleavage • Cleavage – tendency of a mineral to break, or cleave, along flat, even surfaces. • Name directions and angles

  19. Fracture • Fracture – minerals that do not show cleavage when broken are said to fracture.

  20. Other distinctive properties • Odor • Taste • Reaction to dilute HCL • Distinctive feel • Magnetism • Double refraction

  21. Make your own flow chart • What is a flow chart? • type of diagram that represents an algorithm or process, showing the steps as boxes of various kinds, and their order by connecting them with arrows.

  22. Creating a flow chart • What do you want to end with? • Work backwards from your end point to the beginning. • More distinctive properties should be at the end of the flow chart. Grading: Complete on a separate piece of paper and turn in when complete 2o points: A complete chart with all of the identification steps 15 points: A partially complete chart with more than half of the identification steps 10 points: A partially complete chart with less than half of the identification steps 0 points: No chart completed

  23. Cleavage or Fracture Hardness Distinctive Features Nonmetallic luster Luster Mineral Name Metallic luster Hardness Distinctive Features Streak Cleavage or Fracture

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