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Chapter 1 Minerals in the Earth’s Crust

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1 Chapter 1 Minerals in the Earth’s Crust


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

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 Common Silicate Minerals
Feldspar KAlSi3O8 Mica Biotite K(Mg, Fe)3AlSi3O10(F, OH)2 Quartz Silicon Dioxide SiO2

14 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

15 Classes of Nonsilicate Minerals
Native Elements - composed of only one element. Gold Copper

16 Classes of Nonsilicate Minerals
Oxides - form when an element (such as aluminum or iron) combines chemically w/ oxygen. Corundum Al2O3 Aluminum oxide

17 Classes of Nonsilicate Minerals
Carbonates - contain combinations of carbon and oxygen in their chemical structure. Calcite CaCO3

18 Classes of Nonsilicate Minerals
Sulfates - contain sulfur and oxygen, SO4. Gypsum Calcium Sulfate Dihydrate CaSO4·2H2O

19 Classes of Nonsilicate Minerals
Halides - form when: flourine, chlorine, iodine, or bromine combine with sodium, potassium, or calcium Flourite Calcium Fluoride CaF2

20 Classes of Nonsilicate Minerals
Sulfides - contain one or more elements (such as lead, iron, or nickel) combined with sulfur. Galena Lead Sulfide PbS


22 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

23 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


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

26 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

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

28 Submetallic - dull, reflective

29 Nonmetallic Vitreous glassy, brilliant Pollucite

30 Nonmetallic Silky fibrous Gypsum

31 Nonmetallic Resinous plastic Sphalerite

32 Nonmetallic Waxy greasy, oily Cancrinite

33 Nonmetallic Pearly creamy Stellerite

34 Nonmetallic Earthy rough, dull Kaolinite

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


37 Cleavage in calcite

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

39 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


41 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

42 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

43 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 Calcite (red) and willemite (green)

44 Special Property - Salty Taste
DO NOT TASTE MOST MINERALS! Halite is the exception--it will taste salty Borax tastes sweet.

45 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

46 Special Property - Radioactivity
Autunite contains uranium.

47 Special Property - Chemical reaction carbonates react with dilute HCl and other acids by fizzing or bubbling (releasing CO2 gas) CaCO3 + 2HCl = CO2 + H2O + CaCl2 calcite hydrochloric acid

48 Special Property - Optical properties such as double refraction.
Same sample of calcite, but it’s rotated.


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


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


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

55 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

56 Hot Water Solutions This vein of gold was formed this way.

57 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

58 Pegmatites Magma moves upward and forms teardrop-shaped bodies
Examples = topaz, tourmaline can grow to several meters across Pictured here is a sample of tourmaline from a pegmatite.

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

60 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

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

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

63 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

64 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

65 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

66 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

67 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


69 carat the unit used to express the mass of a gemstone
one carat = 200mg

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