Minerals

to

Rocks are made up of ….

…which are either pure elements or compounds,

one or more element combined

5 Characteristics of minerals are:

1. Inorganic2. Solid3. Occurs Naturally4. Definite Chemical

Composition5. Atoms arranged in

a Crystal Structure

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 are made up of compounds

containing Silicon and Oxygen, the two most

abundant elements on Earth.Together, these make up

the chemical group of Silicates!

Rocks that have a high percentage of Silicates

are light in color, and are called Felsic rocks.

High Silica content forms light-colored

rocks.

Rocks that have a low percentage of Silicates

are dark in color, and are called

Mafic rocks.

While lower (but only by about 25%) Silica

content forms darker-colored rocks.

How do Minerals Form???1. cooling magma chambers

where atoms and molecules move closer to form chemical bonds.

• The types of minerals that form depends on the types and amounts of elements present in the magma.

• The size of mineral grains and crystals depends on how long it takes to cool

Olivine

Pyroxene

Peridotite- Mostly Olivine

Gabbro- Pyroxene and OlivineLarge Crystals-Course Texture

Andesite- Hornblend and Biotite? and Plagioclase Feldspar

Potassium Feldspar

Quartz

Pink Granite

Rhyolite – Felsic, fine-grained/volcanic

2. The Pressure Process:

Minerals form when added pressure recrystallizes them by breaking them down and then changing the minerals.

New ions, atoms and molecules recombine in new

ways.

3. Some types of minerals form as water containing

dissolved ions slowly evaporates.

• 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).

How long does it take for minerals to

form??

Minerals are identified and classified by visual inspection, and by

performing simple tests to determine their physical and chemical properties

Color is the most easily observed, but least useful

property because 1 mineral may have many different colors due to impurities.

the way in which a mineral shines in the

light

• Metallic luster makes minerals shine like metals

• Nonmetallic luster means there is some other “shine” to the mineral, but not one that looks like metal

Hardness is the resistance of a mineral to being

scratched.The Moh’s Hardness

Scale is one of the most effective tool for

identifying minerals.

We use a scratch plate to determine

hardness.

the color of a mineral when it’s

powderedMuch 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.This is determined by a mineral’s

crystal structure!!

Basal Cleavage

The tendency of a mineral to break in directions other

than along crystal faces or cleavage surfaces.

Quartz has a conchoidal or shell-like fracture

Conchoidal or shell-like fracture

Fibrous facture

Ratio of a mineral’s mass to an equal volume of water

(Geologists also call this density)

Specific Gravity

Taste

Special Properties

SmellAcid Reaction

Fluorescence

Magnetism

Double Refraction