InorganicNaturally occurrin

g

SolidCrystal Form

Fixed composition

Minerals are…1. Naturally Occurring – to be a

mineral, it must occur naturally

2. Inorganic – does not arise from materials that were once part of living things

3. Solid – a mineral is always solid with a definite volume and shape

Minerals are…4. Crystal structure – a pattern that

repeats over and over with faces that meet at sharp edges and corners

5. Definite Chemical Composition – contains certain elements in definite proportions

a. Element – a substance composed of a single kind of atom

b. Compound – two or more elements chemically combined

gold

water

coal

rubies

petroleum

diamonds

Minerals are identified by their

1. Hardness – a mineral can scratch any mineral softer than itself but will be scratched by a mineral harder than itself

a. Mohs Hardness Scale – ranks minerals from softest to hardest on a scale of one to ten. Talc is the softest known mineral, and diamond is the hardest known mineral.

Minerals are identified by their

2. Color – some minerals are always the same color (malachite is always green and azurite is always blue); most minerals come in a variety of colors

http://www.minresco.com

http://www.gems-afghan.com

http://www.globalcrystals.com

http://www.prettyrock.com

Minerals are identified by their

3. Streak – the color of a mineral’s powder; the color of a mineral’s streak does not change like the color of the mineral may

http://www.uky.edu/KGS

Streak is the color of a mineral powder. Many minerals appear a different color when powdered than they do as a big piece. The color may be entirely different, or it may be a different shade.

http://cmsc.minotstateu.edu

http://cmsc.minotstateu.edu

Minerals are identified by their

4. Luster – how a mineral reflects light from its surface; some ways to describe luster are shiny, earthy, metallic, waxy, and pearly

Copyright © Dr. Richard Busch

Courtesy United States Geological Survey Courtesy United States Geological Survey

Each reflects light differently – that is luster!

Which of these words would you use to describe these minerals?Glassy, metallic, dull, silky, waxy, pearly

Waxy luster

Glassy luster

dull luster

metallic luster metallic luster

Glassy luster

Minerals are identified by their

5. Density – all minerals have a characteristic density; no matter the size of the sample, its density will remain the same

How tightly packed the atoms are will make something heavy.

Every mineral has its own density.

These two items may have the same size – but do not weigh the same.

Why?? Because the brick has atoms that are more tightly packed together than the styrofoam.

This means for equal size, they have their own special weight.

http://www.palagems.com

Which one is worth more?

How could you tell?

The first one is topaz (worth a lot) and the second is citrine quartz (not worth a lot).

A scientist would measure their densities and they would be different!

Minerals are identified by their

6. Crystal System – the crystal structures are divided into six groups

a. Cubic

b. Hexagonal

c. Tetragonal

d. Orthorhombic

e. Monoclinic

f. Triclinic

Copyright © Dr. Richard Busch

http://www.wired-artist-jewelry.comhttp://webphysics.davidson.edu

http://www.fabreminerals.com

http://www.fabreminerals.com

Minerals are identified by their

7. Cleavage and fracture – the way a mineral breaks apart helps us identify it

a. Cleavage – splits apart along flat surface

b. Fracture – breaks apart in an irregular way

Cleavage means it breaks the same way every time.

Fracture means it breaks in a random pattern that cannot be predicted.

www.mrsciguy.com

Calcite and halite break a special way.

donsmaps.com www.visionlearning.com

Quartz and chert break in a random pattern. There is not way to predict how they break.

Minerals are identified by their

8. Special Properties – some minerals are identified by their special properties

a. Fluorescence – minerals that glow under ultraviolet light

b. Magnetismc. Radioactived. Chemically Reactivee. Electrical Properties

Special Properties

MagnetismRadioactivity Chemical Reaction

FluorescenceSalty Taste

But NEVER taste things in the lab!Double Image