Unit 4 Earth’s Crust

1. Unit 4 Earth’s Crust Chapter 10 Minerals, Rocks and Soils

2. Learning Outcomes • Explain how society’s needs led to developments in technologies designed to use rocks. • Classify and describe rocks based on their method of formation: sedimentary, igneous, metamorphic • Explain various ways in which rocks can be weathered: mechanical, chemical • Classify minerals based on their physical characteristics.

3. Minerals • Minerals:naturally occurring inorganic solid materials, composed of one or more elements • Rock: is a mixture of one or more minerals.

4. Minerals • Most minerals are quite rare. • Only a few are common (ex: quartz & mica) Quartz Mica

5. A mineralcan be an element (a pure substance) or a compound (two or more substances). • Some minerals are found in the earths crust (the outermost layer – this is where we live).

6. Granite • Granite is a type of rock that is made up of 4 different minerals. It is made up of quartz, feldspar, mica and hornblende. • Granite is commonly found in the base of statues and in kitchen countertops(once it’s polished).

7. Ways to Identify Minerals: • Hardness (Mohs Hardness Scale) • Shape • Lustre • Colour • Streak • Cleavage & Fracture

8. The MohsHardness Scale • Frederick Mohs developed a scale in 1812 of ten minerals with a “hardness” value of 1-10. • This scale is used to identify different minerals based on its “scratchability”.

9. Mohs Hardness Scale:

10. Minerals • At times minerals appear as crystals. • Crystals occur naturally and they have straight edges, flat sides and regular angles.

11. Shapes of Minerals • All of the minerals (approx 3000) can be found in 1 of 6 crystal shapes.

12. Mineral Examples and Shapes • Halite - Cubic

13. Mineral Examples and Shapes • Wulfenite – tetragonal

14. Mineral Examples and Shapes • Corundum – hexagonal

15. Mineral Examples and Shapes • Topaz – orthohombic

16. Mineral Examples and Shapes • Gypsum – monoclinic

17. Mineral Examples and Shapes • Albite – triclinic

18. Lustre: • Lustre or “shininess” of a mineral depends on how light is reflected from its surface • Example: Gold is a mineral that appears shiny while others such as talc appear dull Talc is a soft mineral. You can scratch it with your fingernail. It comes in many colors such as white, green, pink, and gray.

19. Colour: • Color is one of the most attractive properties of minerals and offers clues into identifying them. • Minerals are not always the same color all the time. For example, the mineral Corundum is white/clear when it’s pure but when there is iron and/or titanium in it, the color is blue (and is called sapphire). When it contains chromium it’s red (and is called a ruby).

20. Streak: • Streak is the color that is left behind when a mineral is rubbed across a piece of an unglazed porcelain tile. • For example: Gold leaves a yellow streak while pyrite (often called fools gold) leaves a greenish-black or brown-black streak. Minerals harder than 7 on Mohs Hardness Scale will not leave a streak

21. Cleavage & Fracture: • Cleavage and Fracture describe how the mineral breaks apart. • If a mineral breaks along smooth, flat surfaces or planes it is said to have cleavage • Mica is an example of a mineral with cleavage

22. Uses of Minerals • Some minerals are so rare and beautiful that they are very valuable such as diamonds. • Some common usages of diamonds: • To make jewelry (rings, earrings, necklaces) • On drill bits to cut through hard substances such as steel and rock • Surgical scalpels, razor blades, dental drills and diamond coated computer parts

23. Uses of Minerals • Your body needs over 20 different elements found in minerals to survive. • For example iron helps the blood carry oxygen. Sodium (in small amounts) helps to regulate water in the body’s cells

24. Other Clues to Mineral Identification • When a mineral breaks apart with rough jagged edges it is said to have fracture • Quartz is an example of a mineral with fracture