1. Earth & Space Science Chapter 4 Minerals

2. Mineral Characteristics Naturally occurring Inorganic (has never been alive) Solid Specific chemical composition (can be an element or a compound) Atoms are arranged in a regular crystal structure Name some minerals…. Is coal a mineral? Salt? Sugar? Glacial ice? Natural gas? Diamond?

3. How Minerals Form Molten magma cools and crystallizes – If cooling is slow, large crystals form – If cooling is fast, small crystals form Minerals can form from solutions – Water can evaporate, leaving mineral crystals behind – Minerals can precipitate from a saturated solution

4. Mineral Identification Luster (metallic or nonmetallic)

5. Mineral Identification Color (not always reliable for identification)

6. Mineral Identification Streak color (scrape against a ceramic tile)

7. Mineral Identification Hardness (how easily it is scratched)

8. Mineral Identification Cleavage/fracture (does it break evenly or with jagged edges

9. Mineral Identification Texture How does it feel? (smooth, rough, glassy, soapy, greasy) Feel these minerals: – Quartz (smooth/glassy) – Graphite (greasy) – Talc (soapy)

10. Mineral Identification Crystal structure

11. Mineral Identification Specific Gravity/Density

12. California in 1849…. How would you tell the difference between gold and pyrite (fool’s gold)?

13. Special Properties Taste (halite) Smell (sulfur) Magnetism (magnetite) Double refraction (calcite-Iceland spar) Effervescence—bubbles—in acid (calcite/carbonates) Fluorescence—glow in the dark (fluorite) Iridescence—color changing (labradorite, bornite)

14. Mineral Groups Sharing similar chemical composition: Silicates: quartz, feldspar, mica Carbonates: calcite, dolomite, azurite Metal oxides: hematite, magnetite Others: – Sulfides: pyrite – Halides: halite – Native elements: copper, silver, etc.

15. Economically Important Minerals Ore: a mineral that contains a useful substance that can be mined profitably – Hematite (iron) – Bauxite (aluminum) Gem: a mineral prized for its rarity and beauty – Ruby – Emerald – Diamond