What is a Mineral?

1. http://www.youtube.com/watch?v=8a7p1NFn64s What is a Mineral?

2. A mineral is… • Naturally occurring • Inorganicsolid • Specific chemical composition • Crystal shape

3. Naturally Occurringnot man made • Salt is a mineral (halite) • Sugar is not • Coal is not a mineral • A mineral is not, nor has ever been alive

4. Crystalline structure • The atoms in minerals are arranged in regular geometric patterns that repeat • Crystal = solid with atoms arranged in repeating patterns

5. Inorganic Solid • Minerals have definite shapes and volumes unlike liquids or gases • Minerals also have specific formulas; example: SiO2, S, Cu, Ag Minerals are inorganic They have never been alive and are not made up from plants or animals

6. Minerals have a definite chemical composition Each one is made of a particular mix of chemical elements have specific formulas; example: SiO2, S, Cu, Ag

7. Mineral or Not? • Coal • Diamond • Dried mud

8. Mineral or Not? • Coal • Not • It’s organic • Diamond • Mineral • Dried mud • Not • No definite crystalline structure

9. Mineral or Not? • Cubic zirconium • Salt • Sugar • Copper

10. Mineral or Not? • Cubic zirconium • Not (man-made diamond imitation) • Salt • Mineral • NaCl, inorganic, cubic crystals • Sugar • Not • Organic • Copper • Mineral

11. What are minerals made of? • Minerals are made of … • elements (Carbon, C, makes up diamonds), • or … • Compounds (quartz is made of silicon dioxide, SiO2) • Salt is made of sodium chloride • (NaCl)

12. Rock Forming Minerals • Of roughly 2000-4000 minerals, only 30 are common • 8 minerals are called rock forming minerals because they make up the rock in the Earth’s crust • Rocks made of 1 or more minerals • Minerals are made of 1 or more elements

13. More than 90% of crust is composed of silicate minerals. Most abundant silicate is feldspar quartz (12%) pyroxenes (11%), micas (5%), and clay minerals (5%). Only 8% of the crust is composed of non-silicates — carbonates, oxides, sulfides,

14. 8 most common “minerals” • Quartz • Feldspar • Mica • Pyroxene • Amphibole • Olivine • Garnet • Calcite

15. Uses for 8 most common rock forming minerals: 1. Quartz -sandpaper, optics, glass, liquid filters, circuit boards, paints, cement , mortar, and jewelry; 2. Feldspar - manufacture of glass products (70%), in ceramics, and fine pottery 3. Mica -used in electronic insulators (mainly in vacuum tubes), ground mica in paint, as joint cement, as a dusting agent, in well-drilling muds, and in plastics, roofing, rubber, and welding rods. 4. Pyroxene – ornamental stone, lithium glasses, pyrex 5. Amphibole – asbestos, construction materials, prefabricated materials 6. Olivine – gemstone peridot, jewelry 7. Garnet - gem 8. Calcite - antacids, cements, concrete, agricultural fertilizers and soil conditioners, limestone building materials and gravel

16. Most Common “Elements” in Earth’s Crust • Oxygen (O) 46.6% • Silicon (Si) 27.7%

17. Most Common Elements in Earth’s Crust • Aluminum (Al) 8.1% • Iron (Fe) 5%

18. Most Common Elements in Earth’s Crust • Calcium (Ca) 3.6% • Sulfur (S) 2.8%

19. Most Common Elements in Earth’s Crust • Potassium (K) 2.6% • Magnesium (Mg) 2.1%

20. How do Minerals Form? • 2 ways • 1. crystallization of magma (cools inside the crust) or lava (cools & hardens on the surface) 2. crystallization of materials dissolved in water. When these liquids cool to a solid state, they form crystals.

21. How do Minerals Form? • What kinds of places allow magma to rise? • Volcanoes, • places where the crust is separating and • places where the crust is very thin (Yellowstone Park)

22. How do Minerals Form? Part I • When magma rises and cools, it forms into minerals • Quick cooling  very small crystals • Slow cooling  larger crystals • Different magma composition  different minerals

23. How do Minerals Form? 2nd way • Often, minerals are dissolved in water • Ever heard of mineral water???? • If the water contains enough of the mineral, it will begin to crystallize in the water Rock Candy = water saturated with sugar + time

24. How do Minerals Form? Part II • We call water that contains so much mineral that it crystallizes out to be… • Supersaturated • Also, crystals can form when the water the mineral is in evaporates

25. Minerals from solutions A liquid is saturated when it becomes full of a dissolved substance and can dissolve no more of that substance. If more of the substance is added to a saturated solution, it is called supersaturated, and mineral crystals form into solids from the solution. Minerals that form from the evaporation of the liquid in which they were dissolved are called evaporates.

26. Minerals are everywhere and used for many things • Look around the room or house. Can you see anything made of minerals?

27. Economic Minerals • Minerals are everywhere and used for many things • Look around the room. Can you see anything made of minerals? • The ceiling is made from gypsum (wall board, etc) • Your pencil “lead” is graphite • All metals are minerals • Glass is melted down sand, essentially • Computer chips are silicon

28. Economic Minerals • A mineral is an economic mineral if it contains a useful substance that can be mined at a profit • ores are rocks that contain minerals in high enough concentration to be economically extracted • Gems are minerals that are prized for their rarity and beauty. Usually perfect crystals • gems

29. Identifying Minerals Geologists identify minerals using tests based on a mineral’s physical and chemical properties, such as • Crystal form • Luster • Hardness • Cleavage • Fracture • Streak • Color • specific gravity • Texture • Density • Special properties

31. Identifying Minerals Scientists use a variety of tests to identify minerals • Crystal form (halite = cube) • Luster (reflect light) • Hardness (scale of 1-10 with 10 = hardest) • Cleavage and fracture (cleavage= splitting along a flat plane; fracture means splitting with jagged edges)

32. 5) Streak (using a porcelain plate) 6) Color 7) Special Properties (react with HCl) 8) Texture 9) Density and specific gravity (pyrite density = 5.2 g/cm3; gold density =19.3g/cm3)

33. Minerals from magma Magma is melted material that forms and accumulates below Earth’s surface is called magma. The type and number of elements in the magma determine which minerals will form. The rate at which the magma cools determines the size of the mineral crystals. Small crystals form from rapidly cooling magma, and large crystals form from slowly cooling magma.