How to Know Minerals

How to Know MineralsChapter 4 Earth Science Book

read pages 46-57restate & answer Topic Questions 1-9

practice the 30 lab mineral samples

common minerals that make up the Earth’s crustRock-Forming Minerals

Topic 1: Page 47 Earth Textbook

* over 2000 minerals known* most are silicates (Si + O + metals)* not always large crystals* mineralogy is the study of minerals

and their properties

simple observations made by looking

Identification by Inspection

Topic 2: Page 47-48 Earth Textbook

*Color*Luster

*Crystal System (shape)

ColorTopic 2: Page 47 Earth Textbook

* first, most easily observed* least useful when identifying minerals

1. impurities change mineral’s colors

2. mineral’s colors are similar3. colors change/react in air

LusterTopic 2: Page 47 Earth Textbook

* Metallic Luster

* Nonmetallic Luster

the way a mineral shines

Metallic LusterTopic 2: Page 47 Earth Textbook

*shines like polished metal

*(galena, pyrite, chalcopyrite)

Nonmetallic LusterTopic 2: Page 47-48 Earth Textbook

*vitreous – shining glass (quartz)*pearly – like a pearl (mica)

*greasy, oily – (talc & graphite)*resinous – like wax (sphalerite)

*dull, earthy – (kaolinite, limonite)*brilliant, adamentine – (diamond)

Crystal System (shape)

Topic 2: Page 47-48 Earth Textbook

*cubic – all 90º, all lengths equal*orthorhombic – all 90º, no lengths equal

*triclinic – none @ 90º*tetragonal – all 90º, some lengths equal

*monoclinic – some @ 90º*hexagonal – 3 axes @ 60º

Identification by Simple Tests

Topic 3: Page 48-50 Earth Textbook

*Streak*Fracture or Cleavage

*Hardness

StreakTopic 3: Page 48 Earth Textbook

* rub mineral on unglazed white tilemetallic - streak dark as mineralnonmetallic - streak colorless to light

the color of a mineral’s powder

CleavageTopic 3: Page 49 Earth Textbook

1 direction – micas, gypsum, talc2 directions – feldspars, hornblende3 directions – galena, halite, calcite

minerals split along flat surfaces

FractureTopic 3: Page 49 Earth Textbook

•concoidal fractures – shell-like fracture•fiberous or splintery – jagged and sharp•uneven or irregular – rough surface

minerals break along non-cleavage surfaces

HardnessTopic 3: Page 49-50 Earth Textbook

*Mohs’ Hardness Scale – page 50 in text•minerals ranked on a scale of 1 to 10•need fingernail, copper, steel, glass, topaz

•1 softest (talc), 7 hardest common (quartz) and 10 is the hardest of all (diamond)

minerals resistance to being scratched

the ratio of the mass of a mineral to the mass of an equal volume of water

Specific GravityTopic 4: Page 50 Earth Textbook

•specific gravity = mass of sample in air mass lost in water

•nonmetals - less than 4 •metals - above 5

weak acid will release bubbles of CO2 Acid Test

Topic 5: Page 51 Earth Textbook

*calcite is calcium carbonate, CaCo3

*dolomite - CaMg(CO3) must be powdered*malachite & azurite are copper carbonates

*calcium carbonate fizzes in acid (HCl)

*limestone & marble calcite

Special PropertiesTopic 6: Page 51 Earth Textbook

•taste – halite is salty•magnetic - magnetite

•flourescence – glows under ultraviolet light, fluorite, sphalerite, willemite

•phosphorescence – glows even after ultraviolet off

•double diffraction – calcite/Iceland par splits images into 2

made with silica tetrahedrons (light colored)Silicates

Topic 7: Page 53-54 Earth Textbook

a) quartzb) feldspars: orthoclase, plageoclasec) micas: muscovite, biotite(black)d) talc

silicates with iron and magnesium (darker)Ferromagnesian Silicates

Topic 7: Page 54-55 Earth Textbook

e) amphiboles: horneblendef) pyroxenes: augiteg) olivineh) garnetsi) kaolinite

made with carbonate group –CO3

CarbonatesTopic 8: Page 55-56 Earth Textbook

•calcite(Iceland spar), dolomite

•malachite, azurite

*Calcium Carbonates

*Copper Carbonates

a metal combines with oxygenOxides

Topic 9: Page 56-57 Earth Textbook

•hematite (reddish-brown streak)•limonite (yellow-brown streak)•magnetite

•corundum

*Iron Oxides

*Aluminum Oxides

•bauxite

a metal combines with sulfurSulfides

Topic 9: Page 56-57 Earth Textbook

•galena•pyrite•chalcopyrite•sphalerite

How to Know MineralsChapter 4 Earth Science Book

read pages 46-57restate & answer Topic Questions 1-9

practice the 30 lab mineral samples