MineralsMrs. Griffin

Hannes Grobe 23:31, 16 December 2006 (UTC

What is a mineral?

• What are some uses of minerals?

• How do we differentiate a mineral from a piece of wood or a human?

• Minerals & history?• What is a rock?

Minerals vs. Rocks

• Earth’s crust is composed of ~ 3000 minerals – which play an important role in forming rocks.

• Rocks are aggregates (mixtures) of minerals. So . . . minerals are the building blocks of rocks.

• A question for the future: How do minerals come together to form a rock?

Minerals

• What is a mineral? Naturally occurring (not man-made) Inorganic, salt vs. sugar Solid (not made of liquid or gas) with a definite

crystalline structure which give it unique physical properties.

Solids have definate shapes and volumes Most are compounds, quartz: oxygen and silicon

Composition and Structure of Minerals

• To understand how minerals form, we need to understand the characteristics of elements and atoms.

• Chemical Elements Elements are the basic building blocks of

minerals. There are over 100 known elements.

Composition and Structure of Minerals

• Atoms Atoms are made up of:

Nucleus, which contains Protons (atomic number)- positive electrical charges and Neutrons - neutral electrical charges (P +N = atomic mass)

Shells which surround the nucleus and contain Electrons - negative electrical charges

• The weight (density) of an element depends on the number of protons and neutrons in the nucleus.

Structureof an Atom

Nucleus

Electron

Nucleus (neutrons &protons)

Chemical Compound

Na+ Cl-

NaCl

Combining Elements to Form Minerals

Elements combine with each other to form a wide variety of minerals (chemical compounds)

The new mineral (compound) will have very different physical properties from the elements that combined to form it

The atoms in minerals are arranged in regular geometric patterns

“Definate” Crystalline Structures

A crystal is a solid in which the atoms are arranged in repeating patterns

Minerals can grow in a closed or open space thus determining its crystalline struture

Chemical Compound

Na+ Cl-

NaCl

“Rock Forming Minerals”

• The most common rock forming minerals are composed of 8 elements: Oxygen (O) , Silicon (Si), Aluminum (Al) , Iron (Fe), Calcium (Ca) Sodium (Na) , Potassium (K) Magnesium (Mg)

• There are just a few dozen minerals that we call the rock-forming minerals.

Most Common Earth crust elements

Oxygen (46.6%), Silicon (27.7%), Aluminum (8.1%), Iron (5%), Calcium (3.6%), Sodium (2.8%), Potassium

(2.6%), Magnesium (2.1%)

Composition of the Crust

• The most abundant elements in Earth's crust are: Oxygen (46.6% by weight) Silicon (27.7% by weight)

The crust

Mineral Groups1. Silicates (96% of crust

minerals) - based upon SiO4

Quartz Feldspar

2. Carbonates – based upon CO3

calcite dolomite rhodochrosite

Carbonates (cont.)

malachite azurite

3. Oxides – combinations of metals and oxygen

hematite magnetite uraninite

4. Sulfides – combinations of metal + sulfur

Pyrite – FeS2

Mineral Resources

• Ore - rock that contains useful metallic minerals that can he mined at a profit.

• Since 98% of the Earth's crust is made up of 8 elements, an element/mineral has to be concentrated at levels above normal for profitable mining.

A Rock

is an

Aggregate

of

Minerals

Quartz Amphibole Feldspar

Identifying Minerals

• Minerals have lots of different properties that help us identify them. Crystal form, Luster, Color, Streak, Hardness, Cleavage, Fracture, Specific gravity, Taste, Smell, etc.

Mineral Color

• Mineral color is often governed by presence of Mg, Fe (dark) or absence of these elements (light).

Mohs hardness scaleMohs hardness scale

10. Diamond 4. Fluorite

9. Corundum 3. Calcite

8. Topaz 2. Gypsum

7. Quartz 1. Talc

6. Potassium Feldspar

5. Apatite

For Next Time

How do minerals "mix" together to form rocks?

What is the rock cycle ?