1. Minerals Naturally formed Solid Inorganic
Not man-made
Solid
Ice is a mineral, liquid water is not
Inorganic
Formed by inorganic processes
Specific chemical composition
Minerals are either chemical elements
Gold and silver
Or chemical compounds in which atom
are present in specific ratios
SiO2 – quartz
Characteristic crystal structure
regular, repetitive geometric patterns

2. Minerals
Because minerals have a crystal structure, they are said to be crystalline
Solids which do not possess a crystal structure are called amorphous solids and are not minerals
glass

3. Identification of Minerals
Properties of Minerals are determined by their compositions and crystal properties
Primary diagnostic properties
Determined by observation or performing a simple test
Several physical properties are used to identify hand samples of minerals

4. Physical Properties of Minerals
Crystal Habit or Form
Geometric arrangement of planar faces that bound a crystal
Habit or form is the external expression of a mineral that reflects the orderly internal arrangement of atoms
Distinctive shape or outward appearance of a particular mineral
pyrite

5. Physical Properties of Minerals
Cleavage
Tendency of a mineral to break in preferred directions along planes of weakness
Mica, halite, calcite

6. Cleavage
Calcite
Halite
Mica

7. Types of Cleavage

8. Physical Properties of Minerals
Hardness
Mineral’s resistance to scratching
Governed by crystal structure and bond strength
The stronger the bonds, the harder the mineral
Mohs relative hardness scale
Relative hardness values can be assigned by determining the ease or difficulty with which one mineral will scratch another
Scale is divided into 10 steps
Talc – 1
Diamond - 10

9. Moh’s Relative Scale of Hardness

10. Moh’s Relative Scale of Hardness

11. Physical Properties of Minerals
Luster
Quality and intensity of light reflected from a mineral
Metallic
Non-Metallic
Vitreous – glassy
Resinous
Pearly
Greasy

12. Luster
Metallic
Nonmetallic - pearly

13. Physical Properties of Minerals
Color
Not always a reliable means of identification
Color is determined by chemical composition
Corundum
Ruby
Sapphire

14. Physical Properties of Minerals
Streak
Thin layer of powdered mineral made by rubbing a specimen on a non-glazed fragment of porcelain

15. Physical Properties of Minerals
Density
Mass per unit volume (g/cm3)
How light or heavy a mineral feels
Galena has a high density

16. Other Physical Properties
Taste
Smell
Reaction to HCL (calcite)
Magnetism (magnetite)
Feel