What is a Mineral?

• It is a naturally occurring , inorganic solid, with a specific chemical composition and a definite crystalline structure

Pyromorphite

What do all minerals have in

common?

All:1. Are formed by natural processes.

2. Are NOT alive and NEVER were alive (INORGANIC)

3. Have a definite volume and shape (hard solid)

4. Are elements or compounds with a uniquechemical makeup

5. Are made up of particles that are arranged in a pattern that is repeated over and over (called a CRYSTAL)

How minerals form?

• They are four major processes by which minerals form:

1. Crystallization of magma.

2. Precipitation

3. Changes in pressure and temperature.

4. Formation from Hydrothermal solutions.

Crystallization from Magma

• When the magma as liquid cools to a solid state, then forms crystals.

• Size of crystals depends on

• 1) the rate at which the magma/lava cools.

• 2) the amount of gas the magma/lava contains,

• 3) the chemical composition of the magma/lava

Precipitation

• The water in Earth’s lakes and rivers beneath its surface contains many dissolved substances. When the water evaporates , some of dissolved materials can react to form minerals.

Pressure and Temperature

• An increase in pressure can cause a mineral to recrystallize while still solid.

• Changes in temperature can cause certain minerals to be unstable. Under these conditions, new minerals can be formed.

Hydrothermal solutions

• It is a hot mixture of water and dissolved substances. They have temperature about 100 -300 C.

Ex: Sulfur minerals , Bornite

Watch Classifying Minerals Clip

Mineral Groups in the Earth’s CrustMinerals that form the rocks within Earth’s crust belong to Seven (7) main mineral groups:

( we will focus on the first three)

1) Silicates

2) Carbonates

3) Oxides

4) Sulfaes

5) Halides

6) Sulfides

7) Native

Hints to Classify Mineral Groups

Olivine (Mg,Fe)2SiO4

Barite BaSO4

Calcite CaCO3

Mineral groups that end with “ate” and have an oxygen group in its chemical formula are one of the following;

Silicates = Si + Ox

Sulfates = S + Ox

Carbonates = C + Ox

A

Mineral Groups

Silicates1) Silicon and oxygen are the most common elements in

earth’s crust.

A mineral group that has silicon and oxygen as part of their atomic structure.

The most dominant mineral class is the silicates.

Comprise more than 96% of the crust. All silicate minerals have the same building block:

Silicon-Oxygen Tetrahedron- consisting of four oxygen ions (negative) surrounding one small silicon ion (positive), forming a tetrahedron, a pyramid shape with 4 identical faces.

Mineral Groups

Silicates1)

Mineral Groups

Silicates1)

Rock forming Silicates are divided into two (2) groups:

Simatic Silicates (Ferromagnesium)

rich in silicon and magnesium (Iron).

main rock type found in the ocean floor and

comprise less than 15% of the crust.

mineral are dark in color.

Mineral Groups

Oxides4)

compounds consisting of an atomic structure of oxygen combined with one or more metals.

most common oxides are those of iron (Fe2O3) and aluminum (Al2O3), referred to as Ore - Minerals.

Halides5) compounds consisting of an atomic structure of chlorine or fluorine

with sodium, potassium, or calcium.

Halite (NaCl) is the most common halide. Often referred to as table salt.

Mineral Groups

Sulfides6)

compounds consisting of an atomic structure of one or more metals combined with sulfur.

common ore mineral. Examples: Pyrite (FeS2), Galena (PbS), Sphalerite (ZnS).

Native Minerals7) elements that occur uncombined in nature.

commonly called native elements.

Examples: Gold (Au), Silver (Ag), Copper (Cu), & Sulfur (S)