MINERALS CH 3

Minerals … Why important? BUILDING BLOCKS of Rocks and Earth’s Crust! Many uses...

Sect 1: Minerals I)Def of Minerals: 5 Characteristics 1) Formed by NATURAL PROCESSES – On or inside Earth. – No input from HUMANS 2) INORGANIC not alive and never was 3) DEFINITE COMPOSITION – Element or Compound 4) CRYSTALLINE – DEF: Atoms arranged in a pattern that is repeated over and over again. 5) Solid

III) 2 processes – Crystals form 1) Crystals from Magma or Lava (Hot melted Rock) – Magma Cools – atoms lose heat energy – Move closer together – combine compounds – Arrange themselves into orderly patterns – *** Type and amount of element determines mineral formed. *** Cool quickly = small crystals (maybe hard to see) *** Cool slowly = large crystals

Crystals cont. 2) Crystals from Solution. (Minerals dissolved in water) HOT or COOL – 1 way: Water evaporates – ions left behind – come together to form crystals. – 2 nd way w/out evap. – too much is dissolved in water. Ions come together and start forming w/in solution

Main Crystal Systems

Changes in Minerals If formed deep in Earth’s crust and mantle – minerals are under high pressure and heat. Minerals can change into new minerals – Tells us what the conditions were like – “history” Breakdown and change from: – Heat & pressure (Inside Earth) – Erosion (Surface) – Water (Surface or within crust) – Wind (Surface) – Ice (Surface)

IV) Mineral Composition 90 elements occur naturally 98% of Earth’s Crust = 8 elements!! 2 most abundant elements = Oxygen & Silicon

5 main mineral groups 1) SILICATES: silicon and oxygen SiO – Common: Feldspar & Quartz (Only one book mentions) 2) CARBONATES: CO 3 – Common: Calcite 3) OXIDES: Fe and O 4) SULFATES: SO 4 5) HALIDES: Na, Cl *Most common Rock forming minerals ~ quartz & calcite

Sect. 2 : Identification of Minerals Unique physical properties that distinguish them. Used to Identify minerals. Scientists don’t use just one …

V) Physical Properties Appearance & color: a starting place – Doesn’t always help. – Ex) Fool’s Gold (Pyrite) & Gold have same color. – Appearance of mineral can change from sample to sample. Look for PHYSICAL PROPERTIES! Hardness – how easily scratched – Don’t confuse hardness w/ ability to break. – Friedrich Mohs: common mineral order of hardness.

Mohs Hardness Scale 1 to 10 P. 89 Shows the scale & how to use it. 1) Talc 2) Gypsum 3) Calcite 4) Fluorite 5) Apatite 6) Feldspar (orthoclase) 7) Quartz 8) Topaz 9) Corundum 10) Diamond – hardest!

More Physical Properties LUSTER: way reflects light – 2 kinds – Metallic: shines like metal ex) chrome, graphite – Nonmetallic: terms used - dull, pearly, silky, glassy Ex) quartz, halite, fluorite Density – mass/volume - Should be able to tell a difference by holding in your hand (if about same volume)

More Physical Properties …. Streak: Color of mineral in powder form. – Take a piece of unglazed tile and rub mineral across. – Leaves a streak of color on tile. – EX) Gold’s streak is yellow but Pyrite’s is greenish black. – EX) Some of you are using streak right now … PENCIL !! Graphite’s streak on your paper

Physical Properties cont. Way a Mineral BREAKS … 2 kinds – Cleavage: breaks along smooth flat surfaces. – Fracture: breaks uneven, rough, jagged surface.

“Special” Physical Properties *Magnetite : attracted to magnets – Ex. Lodestone picks up iron filings like a magnet. *Calcite: fizzes when hydrochloric acid is put on it. * Fluorescence: glows under ultraviolet light.

Sect. 3 Uses of Minerals minerals in our homesminerals in our homes/

Uses & Resources of Minerals 1) Ores: – Mined for PROFIT – Useful = high enough concentration that is worth Taking out. 2) Metallic Resources – most common Fe & Al – Used for buildings, bridges, etc. – Used for food industry 3)Nonmetallic Resources – examples -ceramics, road construction, building stone, sand, -fertilizers

Uses, cont. 4) Rare Metals – scientific and industrial uses -Gold & Platinum -Technology industry -Etc. 5) Gemstones -def: rare and attractive -Used in Jewelry -Used in Industry too. -Diamonds / Corundum: cutting tool or abrasives -Rubies used in lasers

End of Chapter Note Cards done? Read chapter yet? Reviewed all your notes so that they make sense yet? Study! » NOT THIS!!!