1. Properties of Minerals

2. What is a Mineral? Minerals are formed in nature. Minerals are solids.
Minerals have a crystalline,
geometric structure.
Minerals are inorganic; not
made from a living thing.

3. Mineral Properties Colour: minerals come in many different colours
Lustre: the way a surface reflects light / how shiny is it?
Streak: the colour of a mineral in powder form
Cleavage: the tendency of a mineral to break along flat surfaces
Fracture: the tendency of a mineral to break unevenly along curved or irregular surfaces
Hardness: a mineral’s resistance to being scratched
Density: ratio of mass to volume

4. Colour Impurities and other factors can give minerals their colour
These minerals are ALL forms of quartz! Colour is not a reliable way to describe minerals.

5. Colour
Exposure to weather or chemicals may change the colour of minerals.
Pyrite turns grey and black.
Oxidation turns iron from
silver to black to red!
Copper turns green!
Colour is not a reliable property to use in the identification of minerals!

6. Colour Amethyst $68.00 Tanzanite $720.00 Sapphire $500.00 Diamond
$3,000.00
Moissanite
$349.oo
REAL Gold

7. Lustre plastic, dull, metallic, waxy, pearly, glassy, silky waxy
glassy, vitreous
resinous, plastic
silky, fibrous

8. Streak
Colour of the powder made from rubbing a mineral across a streak plate
Some paints are based on powdered minerals
Galena
Pyrite
Hematite

9. Mineral Cleavage & Fracture
Some minerals split along flat surfaces when struck hard--this is called mineral cleavage
Other minerals break unevenly along rough or curved surfaces--this is called fracture
A few minerals have both cleavage and fracture

10. Cleavage
Minerals that break along even lines have cleavage.

11. Types of Cleavage

12. Fracture break along curved or irregular surfaces
Conchoidal, “shell-shaped”
fibrous
irregular

13. Hardness Hardness is the ability to scratch another mineral
Mohs Hardness Scale compares minerals to each other from 1 (talc) to 10 (diamond) using a scratch test
Quartz (most common mineral and most dust particles) is 7
A fingernail can scratch talc.
Quartz can scratch glass,
but fluorite cannot.

14. Density Density tells us how much matter there is in a given space
Density = Mass divided by Volume
Some minerals are very dense eg. galena, magnetite and gold
volume
mass

15. But NEVER taste things in the lab!
Special Properties
Radioactivity
Chemical Reaction
Magnetism
Salty Taste
But NEVER taste things in the lab!
Double Image
Fluorescence