1. Minerals
Earth Science Ch. 2

2. Minerals Minerals are not the same as rocks.
Most rocks are composed of one or more minerals.
Minerals are naturally occurring, inorganic solids with a definite chemical composition and structure.
Minerals can be identified by specific chemical and physical properties.
Minerals are important because of their uses.

3. Characteristics of Minerals
Naturally occurring
Made by natural geologic processes
Not made by people
Inorganic
For the most part minerals do not contain any living material
Solid
At normal earth surface temperatures
Cannot be liquid

4. Definite chemical composition
All minerals are chemical compounds made of 2 or more elements
A mineral that only contains one element is called a native element
Orderly crystal structure
The atoms in a mineral are arranged in an orderly and repetitive manner

5. Most abundant elements
The 4 major elements found in earth’s crust:
Oxygen (47%)
Silicon (28%)
Aluminum (8%)
Iron (5%)

6. Major Rock Forming Minerals
There are 4 rock forming minerals that make up the majority of the earth’s crust:
Quartz
Feldspar
Calcite
Mica

7. Groups of Minerals Silicates
The most abundant group of minerals on earth.
All silicates contain the elements Silicon (Si) and Oxygen (O).
All silicates are formed by structures called tetrahedrons.
2 of the most common silicates found at earth’s surface are quartz and feldspar.
Quartz: used in glass and electronics
Feldspar: used in ceramics

8. The Silicon Oxygen Tetrahedron
4 oxygen atoms surrounding 1 silicon atom

9. Carbonates Composed of the carbonate compound CO3.
Some of the more common carbonates found in our region include calcite and dolomite.
Calcite: used in building materials such as concrete and is very easy to identify because it fizzes when exposed to an acid
Dolomite: construction materials

10. Oxides Composed of oxygen and a metal
The reason why metals are rarely found in their native (uncombined) state is because they bind so easily with other elements such as oxygen.
Some of the more common oxides include hematite and magnetite
Hematite: important ore for iron
Magnetite: used as an iron ore and is easy to identify because it is magnetic

11. Processes that form Minerals
Cooling of magma at the surface
Precipitation which occurs when substances settle out of water and accumulate
Changes in temperature and pressure
Hydrothermal solutions which are very hot mixtures of water and dissolved substances.

12. The most abundant mineral groups found near the earth’s surface are the silicates, carbonates, and oxides.
Silicates form from cooling of magma at the earth’s surface.
Oxides can form in different ways including cooling of magma, precipitation, and heat and pressure.
Carbonates form by precipitation of weathered material.

13. Ore Minerals Pyrite – sulfur, gold, and iron Magnetite – iron
Hematite – iron
Galena – lead
Graphite – carbon
Sulfur – sulfur

14. Properties of Minerals
Color
Most easily seen but the least useful in identification because even small amounts of different elements can change color.
Streak
The color of a mineral in its powdered form
Determined by rubbing the mineral against unglazed tile
Color may change but streak never does.
Luster
Used to describe how light is reflected from a surface
Many terms can be used but the most common are metallic and nonmetallic

15. Crystal form Hardness Arrangement of atoms
There are 6 different crystal systems
Hardness
Resistance of a mineral to being scratched
Mohs hardness scale goes from 1 (softest) to 10 (hardest)
As you move up the scale, the mineral is harder to scratch

16. Cleavage and fracture Density The way that a mineral breaks
The arrangement of the atoms in a mineral will determine if it will cleave or fracture
Cleavage: the mineral breaks along flat even surfaces
Fracture: the mineral breaks along uneven surfaces
Density
Relationship of mass to volume
The formula is used D=m/v
Mass can be determined by using a triple beam balance or scale
Volume can be determined by using a graduated cylinder

17. Distinctive properties of minerals
Graphite and talc have distinctive feels
Metallic minerals are easy to shape
Magnetite is magnetic
Transparent calcite displays double refraction
Sulfur is easily identified by its smell
Carbonates fizz when an acid is dropped on them.