How to Know How to Know Minerals?Minerals?

KWLHWhat do you know about minerals?

What do you want to know about them?

What did you learn?

How did you learn it?

Mineralogy is the study of minerals and their properties.

Rock-Forming MineralsRock-Forming MineralsMinerals make up the Earth’s crust

* over 2000 minerals known

Identification by Identification by InspectionInspection

simple observations made by looking* Color* Luster

* Crystal System (shape)

ColorColor* most easily observed

* least useful when identifying minerals… but why???but why???

1. impurities change the colors

2. colors are similar

3. Colors react to the air or its temperature

You see… colors are similar!You see… colors are similar!

LusterLusterthe way a mineral shines

* Metallic Luster

* Nonmetallic Luster

Metallic LusterMetallic Luster*shines like polished metal

(galena, pyrite, chalcopyrite)

Nonmetallic LusterNonmetallic Luster*vitreous – shining glass (ambar)

*pearly – like a pearl (mica)

*greasy, oily – (graphite)

*resinous – like wax (sphalerite)

*dull, earthy – (kaolinite, limonite)

*brilliant – (diamond)

Crystal System (shape)Crystal System (shape)

WHAT IS A KARAT?

A carat (UK) or karat (US) is a unit of weight for diamonds and other gemstones.

One carat equals 200 milligrams (0.200 grams). There are 453 grams in a pound (1,000 grams to a kilogram).

Therefore, if your fiancee weighs 170 pounds, you have a 385,050-carat fiancee!

A karat, when used with gold, is a unit of purity- 24-karat gold is pure gold, but usually you mix gold with a metal like copper or silver to make jewelry (because pure gold is too soft).

Identification by Identification by Simple TestsSimple Tests

StreakStreakthe color of a mineral’s powder

* Rub a mineral and check its color

CleavageCleavageminerals split along flat surfaces

FractureFracture

HardnessHardnessminerals resistance

*Mohs’ Hardness Scale

Special PropertiesSpecial Properties•taste – flavor

•magnetic - magnetism

•flourescence – glows under ultraviolet light

•phosphorescence – glows even after ultraviolet off

•double diffraction – splits images into 2

KWLHWhat do you know about minerals?

What do you want to know about them?

What did you learn?

How did you learn it?