M INERALS OF THE E ARTH ’ S C RUST Chapter 1

W HAT IS A MINERAL ? Section 1 Vocabulary Mineral Element Compound Crystal Silicate Mineral Nonsilicate Mineral

T HE F OUR E SSENTIAL Q UESTIONS Is it nonliving material? Is it a solid? Does it have a crystalline structure? Is it formed in nature?

M INERAL S TRUCTURE Four questions Needs to be a yes for all 4 Crystalline Structure Need to know about elements Elements All minerals contain one or more 92 naturally occuring elements

A TOMS AND C OMPOUNDS One kind of element Atom-smallest part of an element that has all the properties of that element Compound Halite-NaCl Compound Na-Sodium Cl-Chlorine One Element Gold or Silver Native element

C RYSTALS Shape-by the arrangement of the atoms within the crystal Arrangement-by the kinds of atoms that make up the mineral Definite crystalline structure Crystal Classes

T WO G ROUPS OF M INERALS Most common classification of minerals is based on chemical composition Silicate minerals Nonsilicate minerals

S ILICATE M INERALS Silicon and oxygen Two most common elements in the Earth’s crust Combination 90% Combine with other elements

N ONSILICATE M INERALS Do not contain silicon and oxygen Most important classes Native elements Carbonates Halides Oxides Sulfates Sulfides

I DENTIFYING M INERALS Section 2 Vocabulary Luster Streak Cleavage Fracture Hardness Density

C OLOR Same mineral-variety of colors Quartz Granite Change of color Impurities Other factors Air Water NOT THE BEST WAY TO IDENTIFY A MINERAL

L USTER The way a surface reflects light Shiny or dull Metallic-Shiny, bright, and reflective Submetallic-dull and reflective Nonmetallic-dull and not reflective Figure 1

S TREAK The color of a mineral in powered form Streak Plate-a mineral’s streak can be found by rubbing the mineral against a piece of unglazed porcelain Color is not always the same Not affected by air or water MORE RELIABLE THAN COLOR

C LEAVAGE AND F RACTURE The way a mineral breaks is determined by the arrangement of its atoms. Cleavage-break smooth Fracture-uneven break

H ARDNESS A mineral’s resistance to being scratched MOHS HARDNESS SCALE Talc-1 Diamond-10 The greater a mineral’s resistance to being scratched is, the higher the mineral’s rating is. Scratch it on another rock

D ENSITY The measure of how much matter is in a given amount of space. Density=Mass/Volume Grams per cubic centimeter (g/cm 3 ) Water is used as a reference point. 1 g/cm 3 Specific Gravity

S PECIAL P ROPERTIES Only a few minerals! Fluorescence-glow under ultraviolet light Magnetism-attract iron Chemical Reaction- acid will cause a fizz Taste-halite-salty Optical Properties- double image Radioactivity- radium or uranium

T HE F ORMATION M INING AND U SE OF M INERALS Section 3 Vocabulary Ore Reclamation

M INING Must be mined to extract valuable elements To describe a mineral deposit large enough and pure enough to be mined for profit Two Forms Surface Mining Subsurface Mining Depends on Location

S URFACE M INING At or Near the Surface Open pits- remove large, near-surface deposits of economically important minerals Gold/silver Downward layer by layer Explosives Surface Coal Mines-strip mining-moved in strips Quarries-used for mining building stone, crushed rock, sand, and gravel

S UBSURFACE M INING Too deep within the Earth to be surface mined Passageways Horizontally At an angle If deep in the earth a vertical shaft is sunk Connects passageways at different levels

R ESPONSIBLE M INING Return the land to its original state after the mining is complete Law since mid-1970’s Reduce needs for minerals Recycling

M ETALLIC M INERALS Shiny Surfaces Does not let light pass through them Conductors of heat and electricity Strong, Do not Rust Gold, Silver, and Copper

N ONMETALLIC Shiny or dull surfaces May let light pass through them Good insulators of electricity Most Widely used Calcite and Silica

G EMSTONES Highly Valuable Diamond, Ruby, Sapphire, etc. Color is most important More attractive the more value Durable Carat