Elements and Compounds in their

solid form make up…

What is a Mineral?

A Mineral is a naturally

occurring Inorganic Solid with a

definite chemical composition and

a crystalline structure.

That means that…

•It can’t be organic in

origin

•It can’t be a liquid

and..

•It has to have a crystal

structure

Lets put that in a list format.

1. Minerals are a naturally occurring

substance.

2. Minerals are solids.

3. Minerals have a definite

chemical composition.

4. The atoms that make up minerals

are arranged in an orderly pattern

(They form crystals).

5. Minerals are inorganic. (They

were never alive.)

How many different minerals are

there on Earth???

Answer:About 4,000

More than 90% of all of the

minerals in the Earth’s Crust,

however, are made up of

compounds containing Silicon

and Oxygen, the two most

abundant elements on Earth.

Silicates

• Chemical Compounds of Oxygen and

Silicon

And…..

The percent composition of Silicate

Minerals in an igneous rock determine a

lot of the characteristics of that rock and

the magma that formed it.

High Silica content forms light-

colored rocks.

While lower (but only by about

25%) Silica content forms

darker-colored rocks.

How do Minerals Form???

1. Minerals form in cooling magma chambers

Different types of minerals

crystallize at different temperatures

Decreasing temperature

Mineral formation in a Magma Chamber

Bowen’s Reaction Series

Olivine

Pyroxene

Peridotite- Mostly Olivine

Gabbro- Pyroxene and Olivine

Andesite- Hornblend and Biotite? and

Plagioclase Feldspar

Potassium Feldspar

Quartz

Pink Granite

Mineral Fractionalization in a Magma Chamber

2. Metamorphic Minerals:

Some minerals occur as the

result of Recrystallisation and

Reaction within existing rocks

which produces new minerals

in response to changes in

and

3. Some types of minerals form

as water containing dissolved

ions slowly evaporates.Salt deposits

How long does it take for

minerals to form??• Minerals in solution in water can form

relatively quickly when the water

evaporates.

• Minerals in magma can form as quickly as

the magma/lava can crystallize (lava can

cool in minutes, while magma can take

thousands of years).

A Crystal is….

A regular geometric solid with

smooth surfaces called….

The orderly arrangement of ions,

molecules, or atoms, in any

mineral determines the shape of

its crystals.

Although there are thousands of

different types of minerals, their

crystals come in six basic types

of shapes

Cubic

• Looks like a cube or one die/dice

Orthorhombic

• The sides A, B, and C all have to be

different

simple base-centered body-centered face-centered

Tetragonal

• A is not equal to C

• It is basically a stretched out cube

Triclinic

• Similar to Orthorhombic but no angles are equal

• Like a prism with unequal angles

Hexagonal

• Looks like a hexagon

• All sides are equal and all angles are equal

Monoclinic

• Opposite angles do not measure 90 degrees

List properties of this mineral

Minerals are identified and

classified by visual inspection, and

by performing simple tests to

determine their physical properties

Only 30 of the 4,000 known

minerals are common.

These 30 minerals are known

as the rock-forming minerals

Most rock-forming minerals

are…

The percent composition

of Silicate minerals in a

rock determines the type

of rock it is.

Rocks that have a high percentage

of Silicates are light in color, and

are called Felsic rocks.

Rocks that have a low

percentage of Silicates are dark

in color, and are called

Mafic rocks.

Rocks are often made of several

different minerals.

Minerals are most often

identified by inspecting their

Physical and Chemical

properties.

Color is the most easily observed, but least

reliable property of a mineral for

identification.

This is because the color of many minerals

varies with the kind of impurities in the

mineral.

Luster is the way in which a mineral shines in the light.

Types of Luster

Metallic Non-Metallic

Streak is the color of the powder left

on a streak plate when a mineral is

rubbed on it.

Streak is much more reliable than

color because, although the color

of a mineral changes, its streak

does not.

Cleavage is the tendency of a mineral

to split in a particular direction.

“Sheety” Cleavage

Feldspars always cleave readily at or near right angles.

Fracture is the tendency of a

mineral to break in directions other

than along crystal faces or cleavage

surfaces.

Conchoidal or shell-like fracture

Fibrous facture

Hardness is the resistance of a mineral to

being scratched.

The Mohs Hardness Scale is one of the

most effective tool for identifying

minerals.