minerals edited ppt

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Rocks & Minerals NOTES

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Page 1: Minerals edited  ppt

Rocks & MineralsNOTES

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MineralA Naturally Occurring Naturally Occurring Inorganic Solid Inorganic Solid with a definite chemical chemical composition composition and crystaline structurecrystaline structure.

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Mineral Properties & Identification

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Crystal structure & chemical composition of minerals largely determine physical & chemical

properties used to identify

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What causes minerals to have different physical properties?

their internal arrangement of atoms

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The Main Physical Properties Used to Identify Minerals

Color

A poor indicator!

Minerals can be multiple colors

Many minerals are the same color

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The Main Physical Properties Used to Identify Minerals

Streak

the powder form of a mineralmore reliable than color

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Streak-Color of finely crushed residue or powder of a mineral

-When you write on chalkboard, you observe streak of chalk

-Streak of mineral usually consistent, making streak color more useful in identifying than mineral color

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The Main Physical Properties Used to Identify Minerals

Luster

how light reflects off a mineral

metallic non-metallic

looks like a metal

looks earthy, waxy, greasy or brilliant

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Luster- Shine from an unweathered mineral’s surface- Way a mineral looks in reflected

light- 2 groups of luster

Metallicshine like surface of clean stainless steel potExample: Pyrite & galena

Non-Metalliccan be glassy like black hornblende & quartzcan be pearly like muscovite mica

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Hardness

The Main Physical Properties Used to Identify Minerals

resistance to being scratched

It is NOT the same as breaking!

For example: You can break glass easily with steel.However, steel will not scratch glass.

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Hardness

The Main Physical Properties Used to Identify Minerals

Scratchability of minerals, not how easily it breaks

For example: Diamonds are hardest mineral, but if you

drop an unmounted diamond on a tile floor it will break

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MOH’S SCALE OF HARDNESS

Hardness

Mineral Hardness

Mineral

1 (softest)

Talc 6 Orthoclase

2 Gypsum 7 Quartz3 Calcite 8 Topaz4 Florite 9 Corundum5 Apatite 10

(hardest)Diamond

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- Quick way to determine relative hardness is to use piece of window glass1. If mineral scratches glass it is hard2. If mineral doesn’t scratch glass it is soft

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Density-Each mineral has specific density or

narrow range of densities-Often stated as specific gravity,

which has no units-Specific gravity is density of mineral

compared to density of water-density is a good test to distinguish

gemstones, because it doesn’t harm samples

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Cleavage- Tendency of mineral to break along

zones of weakness & form smooth to semi-smooth parallel sides or surfaces

- Cleavage surfaces can often be distinguished from sides without by having a shiner or more brilliant luster

- If minerals lack preferred zones of weakness, then it will demonstrate uneven breaking surface (fracture)

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Fracture

The Main Physical Properties Used to Identify Minerals

the mineral breaks randomly

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Crystal Structure

-Outward geometric shape of mineral, crystal form, reflect structure

-Orderly arrangement of atoms in mineral

-Any mineral can have many different crystal shapes

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Other Mineral Properties- Some chemical properties of

minerals are used for identification- Reaction of a mineral with

acid