MINERALS CH 3. Minerals … Why important? BUILDING BLOCKS of Rocks and Earth’s Crust! Many uses...

MINERALS

CH 3

Minerals …

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

Sect 1: MineralsI)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.–2nd 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: CO3

– Common: Calcite

3) OXIDES: Fe and O• 4) SULFATES: SO4

• 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 10P. 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 homes/

Uses & Resources of Minerals

• 1) Ores:– Mined for PROFIT– Useful = high enough concentration that is worthTaking 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!!!