Occurs naturally

Is a solid

Has a definite chemical composition

Has atoms arranged in an ordinary pattern (crystal structure)

Is inorganic (not alive)

Made of 2 or more elements Example:

Quarts: silicon & oxygen Halite: sodium & chlorine Galena: lead & sulfur

Minerals with only one element are called Native Minerals (native element)Examples:

GoldSilverCopperSulfurDiamonds (carbon)

1. Magma

Atoms move freely in liquid magma

As magma cools & hardens atoms come

closer together to form solid mineral

Depending on the atoms different minerals

can form from the same magma mass

Rate of cooling determines the minerals

grain size

2.Evaporation

Water containing dissolved ions evaporates

Ions come together to form a mineral

3. Metamorphic minerals

Minerals can also be changed into other minerals

They recrystallize due to changes in

Heat

Pressure

Chemical action of water

All minerals are crystalline: atoms arranged in a

regular pattern

A crystal is a regular geometric solid with smooth

surfaces called crystal faces.

Arrangement of ions (atoms with a positive or

negative charge) determines the shape of the

crystal

The angle at which crystal faces meet is always the

same for each kind of mineral (can use to identify)

If you can’t see a crystal shape (face) it is because space is too limited, atoms of 1 crystal join to another & faces (shapes) are lost

A. Silicates Made from silica tetrahedrons1. Quartz

Second most abundant mineral in Earth’s crust2. Feldspar

60% of the crust, framework silicate Divided into 2 groups Potassium feldspar: most common orthoclase Sodium-Calcite feldspar: plagioclase Example: Albite & Oligoclase

3. Mica Very soft, sheet silicate White mica (muscovite) Dark Mica, black or brown (biotite)

4. Talc The softest mineral

5. Amphiboles Most common is hornblende, which is a ferromagnesium silicate Can belong to almost any silicate family

6. Pyroxenes Most common is augite Also ferromagnesium silicate

7. Olivine Single silica tetrahedron

8. Garnets Very hard

9. Kaolinite or Kaolin Formed by weathering of feldspar and other silicate minerals

Isolated tetrahedra: silicon-oxygen tetrahedra that are linked only by atoms of elements other than silicon and oxygen (1 Si & 4 O)

Ring Silicates: tetrahedra are joined into 3, 4, or 6 sided rings by shared oxygen atoms

Single-chain silicates – each tetrahedron is bonded to 2 others by shared oxygen atoms

Double-Chain Silicates: 2 single chains of tetrahedra bonded (linked) to each other

Made of one carbon atom combined with three oxygen atoms1. Calcite (Calcium)

Most common Colorless calcite is iceland spar (ice-like)

2. Dolomite (magnesium) Coarse or fine grains Doesn’t react as much to acid test as calcite

3. Malchite and azurite (copper)4. Siderite (iron)

1. Hematite

Most common iron oxide

Leaves red-brown streak

2. Magnetite Black magnetic iron oxide

Example: Lodestone

3. Pyrite Most common iron sulfide

1. Shape of its crystalsEx: Halite (table salt) crystals

are isometricno matter how large or small

they have to be the same shapeTest: look under dissecting

microscope

2. ColorsSome minerals have more than one colorImpurities in a mineral can change its color

Ex: Quartz- clear, with iron-purple, with titanium-pink

Exposure to air changes colors Ex: Brass is yellow-air is bronze

Bronze is brown – air is purpleTest: simple look at it

3. Luster – the way a mineral reflects light Two types 1. Metallic: looks like metal 2. Nonmetallic: does not look like metal

Ex: glassy, earthy, pearly etc.

Test: look at the mineral, ask yourself ‘does it look like a piece of metal’ If it does than it is metallic if not then nonmetallic

The way a mineral shines in a light

Either metallicmetallic or nonmetallicnonmetallic

4. CleavageMost minerals break in a particular pattern1.Cleavage

If breaks along flat surfaces it forms a sheet If breaks in three directions that are at right angles

2. Fracture: if a mineral breaks in more than one direction If a mineral breaks on a curved surface (conchoidal

fracture)

Test: look at sides and compare to examples. If it is flat then cleavage, if not then fracture

“Sheety” Cleavage

Fluorite cleaves

at right angles

Conchoidal or

shell-like fractureFibrous facture

CLEAVAGECLEAVAGE FRACTUREFRACTURE

in

5. HardnessDepends on the arrangement of its atoms and

the strength of the bondThe harder mineral will always scratch the softer

oneMoh’s scale: shows hardness of minerals

The higher the number the harder the mineral

Test: use hard points to gently wipe across the mineral. Each point is worhta certain number, as soon as the point scratches the mineral you stop. That is the number

6. Streak: indicator of true colorStreak is the same for all samples of

the same mineralHard minerals leave no streaks

Test: scratch the mineral on an unpolished porcelain tile. The powder left behind is the true color

7. Specific Gravity (Heft): ratio of the weight of a mineral to the weight of an equal volume of waterSpecific gravity is always greater than 1Nonmetallic- less than 3Metallic – about 5Gold if pure – 19.3

Archimede’s principle – loss of weight is equal to the weight of the displace water

Formulas:

Specific Gravity = weight of sample in air weight of equal volume of water

or

= weight of sample in air loss of weight in water

Example: A mineral weighs 50 Newtons in air and 30 Newtons in water

Specific Gravity = 50 N(50 N – 30 N)

=50 N20 N

= 2.5

So, the mineral is 2.5 times as heavy as an

equal volume of water

Test: Use a Newton scale and attach a mineral to the scale. Then find the weight in air and then place mineral in water (without touching side) to find weight in the water. Finally use the specific gravity formula

8. Acid Test: to find if a mineral is a carbonate Place a small drop of weak hydrochloric acid on a mineral. If mineral bubbles it has carbon, if not it doesn’t

9. Special Properties of Minerals: Magnetic: use a magnet and see if it sticks

Taste: certain minerals have a specific taste *never taste a mineral without being told to

Fluorescence: glowing while under a U.V. light

Phophorescent: continues to glow after the U.V is off

Radioactive: test minerals with a Geiger counter

Double Refraction: splits light rays into two parts (will see a double image) look through mineral for image