Chapter 1 Minerals in the Earth’s Crust

1. Chapter 1Minerals in the Earth’s Crust

2. SECTION 1

3. mineral • a naturally formed, inorganic solid that has a definite crystalline structure Must be able to say “yes” • 1. must be a solid • 2. must be a nonliving material • 3. must have a crystalline structure • 4. must be formed in nature (not by man)

5. elements • pure substances that cannot be broken down into simpler substances by ordinary chemical means

6. compound • a substance made of two or more elements that have been chemically joined or bonded • NaCl = Sodium + Chlorine = salt • H2O = Hydrogen + Oxygen = water

7. native element • a mineral composed of only one element Example: gold and silver

8. General Facts about Minerals • Between 2 - 3,000 have been identified • A few are “native elements” -- made of only one element, such as sulfur, gold. copper, and graphite (carbon) • Most are compounds, especially the silicate group (Si, O). • Other important groups are oxides, carbonates, and sulfides.

9. Less than a dozen are common in most rocks Olivine Amphibole (group) Magnetite, limonite, and other iron oxides Pyrite Quartz Feldspar (group) Muscovite (white mica) Biotite (black mica) Calcite Pyroxene

10. Common uses include: • Aluminum--packaging, transport, building • Beryllium--gemstones, fluorescent lights • Copper--electric cables, wires, switches • Feldspar--glass and ceramics • Iron--buildings, automobiles, magnets • Calcite--toothpaste, construction • http://www.mii.org/commonminerals.php

11. crystals • solid, geometric forms of minerals produced by a definite repeating pattern of atoms that is resent throughout the mineral

12. silicate minerals • a mineral that contains a combination of silicon, oxygen and one or more metals • make up more than 90% of Earth’s crust • silicon and oxygen combine with other elements such as aluminum, iron, magnesium and potassium to make up silicate materials

13. nonsilicate minerals • minerals that do not contain a combination of the elements silicon and oxygen • some made up of carbon, oxygen, fluorine and sulfur • native elements, oxides, carbonates, sulfates, halides & sulfides

14. SECTION 2

15. Minerals are identified by their key characteristics • hardness • crystal shape (form) • luster • color • streak • cleavage/fracture • density (specific gravity) • special properties --reaction to acid --fluorescence --salty taste --magnetism

16. COLOR • results from ability to absorb some wavelengths and reflect others • some minerals have characteristics colors • others vary due to chemical differences or impurities (atoms mixed inside the main elements) • because of factors such as impurities, color is not the best way to identify a mineral

17. COLOR

18. LUSTER • Describes how light reflects off the surface • “shiny” = metallic luster • “dull” = submetallic or nonmetallic luster

19. STREAK • Color of the powder when rubbed on a “streak plate” (unglazed porcelain) • can be found by rubbing the mineral against a piece of unglazed porcelain • powdered color is not always the same color of the mineral sample

20. Streak Plate = a piece of unglazed porcelain used to test the streak of minerals

21. Cleavage of mica into thin sheets Cleavage = the tendency of some minerals to break along smooth, flat surfaces

22. fracture in obsidian fracture = the tendency of some minerals to break unevenly along curved or irregular surfaces

23. Cleavage in calcite

24. HARDNESS • a mineral’s resistance to being scratched • the greater a mineral’s resistance to being scratched, the higher the rating • Mohs scale from 1 (talc) to 10 (diamond) • Quartz (most common mineral and most dust particles) is 7

25. MOHS HARDNESS SCALE

26. DENSITY (Specific Gravity) • All minerals have density (mass / volume), but some are very dense • Examples include galena, magnetite, and gold • Specific Gravity is the density of the mineral compared with density of water

27. SPECIAL PROPERTIES • particular to only a few types of minerals – need specialized equipment to determine these properties EXAMPLES: fluorescence, chemical reaction, optical properties, magnetism, taste, radioactivity

28. Special Property-the “Acid Test” Carbonates react with dilute HCl and other acids by fizzing or bubbling (releasing CO2 gas)

29. Special Property - Fluorescence • Some minerals will glow when placed under short-wave or long-wave ultraviolet rays • Franklin and Ogdensburg NJ are famous for their fluorescent minerals

30. Special Property -Salty Taste • DO NOT TASTE MOST MINERALS! • Halite is the exception--it will taste salty

31. Special Property -Magnetism • Many iron minerals will produce an invisible magnetic force field • “Lodestone” was used by Vikings more than 1,000 years ago as compasses

32. SECTION 3

33. Evaporating Salt Water • when a body of salt water dries up/evaporating these minerals crystallize • Examples = gypsum and halite

34. Limestones • surface water & groundwater carry dissolved materials into lakes & oceans where they crystallize on the bottom • Examples = calcite and dolomite

35. Metamorphic Rocks • when changes in pressure, temperature or chemical makeup alter a rock • Examples = calcite, garnet, graphite, hematite, magnetite, mica and talc

36. Hot-Water Solutions • Groundwater works its way downward and is heated by magma, then reacts with minerals to form a hot liquid solution. Dissolved metals and other elements crystallize to form new minerals. • Examples = gold, copper, sulfur pyrite and galena

37. Plutons • when magma rises upward through the crust and stops before reaching the surface it cools slowly forming millions of mineral crystals – it eventually solidifies to form a pluton • Examples = mica, feldspar, magnetite and quartz

38. Pegmatites • Magma moves upward and forms teardrop-shaped bodies • Examples = topaz, tourmaline • can grow to several meters across

39. ORE • a mineral deposit large enough and pure enough to be mined for profit • removed by two methods = surface or subsurface mining

40. SURFACE MINING • When mineral s deposits are located at or near the surface of the earth • kinds = open pits, surface coal mines and quarries • surface coal mining also called strip mining

41. OPEN PIT MINING • used to remove large, near-surface deposits of economically important minerals such as gold and copper

42. QUARRIES • open pits that are used to mine building stone, crushed rock, sand and gravel

43. SUBSURFACE MINING • when mineral deposits are located too deep within the earth’s to be surface mined • often requires passageways to be dug into the earth to reach the ore

44. RECLAMATION • the process of returning land to its original condition after mining is completed • required by law   • reduces the potential harmful effects of mining to return the land to its original state after mining is completed

45. METALLIC MINERALS • have shiny surfaces, do not let light pass through them and are good conductors of heat and electricity • can be processed into metals that are strong and do not rust, can be pounded into various shapes or stretched thinly without breaking

46. NONMETALLIC MINERALS • have shiny or dull surfaces, may let light pass through them and are good insulators of electricity • most widely used minerals in industry

47. GEMSTONES • nonmetallic minerals that are highly valued for their beauty and rarity rather than their usefulness • diamond, ruby, sapphire, emerald, aquamarine, topaz and tourmaline • color is the most important characteristic of a gemstone • must be durable and hard enough to be cut and polished

49. carat • the unit used to express the mass of a gemstone • one carat = 200mg