All the rocks and minerals in the Earth’s lithosphere are made of elements, but not all rocks are minerals. To be classified as a mineral it must be: 1. A solid 2. Naturally occurring 3. Inorganic 4. Have a crystal structure 5. Has a definite chemical composition.

There about 4000 known minerals, however of all the elements in the Earth’s crust, only a mere eight make-up 98.5% of the crust total mass. Of those eight elements, more 90% of the minerals are compounds containing only two. 1. Oxygen – 46.6% 5. Calcium – 3.6% 2. Silicon – 27.7% 6. Sodium – 2.8% 3. Aluminum – 8.1% 7. Potassium – 2.6% 4. Iron – 5% 8. Magnesium – 2.1%

The formation of minerals is a process known as crystallization. There are three main ways minerals crystallize: 1. Magma Process 2. The Pressure Process 3. Crystallization from solution

Convection currents deep in the Earth’s mantle cause magma to rise and begin to cool. As the magma cools, atoms, molecules, and ions arrange themselves into regular, repeating patterns and bond forming various crystals.

1. Pressure chemically breaks down the rock 2. Heat and pressure change the rock’s properties without melting the rock 3. The atoms, ions, and molecules recombine to form new minerals

When water cools or evaporates, the particles of dissolved minerals come together again and crystallize.

Every mineral has a unique set of physical properties that are used to identify it. These properties include: 1. Color 2. Luster 3. Hardness 4. Streak 5. Cleavage 6. Fracture 7. Density 8. Specific Gravity

Color is the easiest of all properties to observe however, it is the least reliable.

Luster describes the way a mineral surface reflects light. Lusters include: 1. Metallic 2. Nonmetallic 3. Greasy 4. Dull 5. Earthy 6. Glassy 7. Pearly

Hardness is a mineral’s resistance to being scratched. Mineralogist Friedrich Mohs devised a numeric scale to determine the hardness of a mineral.

The streak of a mineral is the color of its powder. Streak is obtained by rubbing the mineral on a streak plate.

Cleavage is a mineral’s tendency to split along smooth, flat surfaces.

Fracture occurs when a mineral breaks along rough or irregular surfaces.

Special type of fracture that occurs in glassy type minerals.

Many minerals have similar densities however, very high or low densities can be used to identify certain minerals. Examples: Pumice:.64 g/cm 3 Platinum: 21.5 g/cm 3 Formula:

A mineral’s specific gravity is the ratio of its dry mass to the mass of an equal volume of pure water. In general, the specific gravity of a mineral tells you how many times denser the mineral is than pure water. Formula: Specific Gravity = ______Dry Mass______ (Dry Mass) – (Wet Mass)

Some minerals have unusual characteristics that can be used to identify specific minerals.

Double Refraction occurs when a single light wave is split into two. Example: Iceland spar

When certain minerals are exposed to ultraviolet light they will glow.

Minerals such as calcite and halite have a salty taste.

Minerals such as lodestone and magnetite are naturally magnetic.

Some minerals such as carnotite and uraninite give off radiation that can be detected using a Geiger Counter.

Minerals are classified according to similarities in composition. Minerals are classified into four main groups: 1. Silicates 2. Carbonates 3. Oxides 4. Sulfides

Silicates are any minerals that contain silicon and oxygen. The basic building block of a silicate is the silica tetrahedron.

Properties Quartz SiO2 Color Colorless, rose, amethyst, smoky LusterGlassy Hardness7 StreakWhite BreakConchoidal Density1.2 g/cm 3 Specific Gravity2.65 Crystal StructureSilica Tetrahedron Special Properties-

The feldspar family makes up approximately 60% of Earth’s crust The molecular difference between quartz and feldspar is that the silicone atom is replaced by either an aluminum, potassium, sodium, or calcium atom. Feldspar is classified into two main groups: 1. Orthoclase Feldspar: Potassium atom 2. Plagioclase Feldspar: Sodium-calcium atoms

PropertiesOrthoclase FeldsparPlagioclase Feldspar ColorSalmon with parallel white fibers White to gray StreakWhite Hardness66 LusterPearly Crystalline Structure Silica Tetrahedron BreakCleavage (two directions) Density Specific Gravity2.5 – 2.6

Orthoclase Feldspar Plagioclase Feldspar

Pyroxene Family: Ferromagnesian Properties Augite (Ca,Na)(Mg,Fe,Al)(Al,Si)2O6 ColorBrownish green LusterGlassy Hardness5 – 6.5 StreakGreenish gray BreakCleavage Density1.2 g/cm 3 Specific Gravity2.65 Crystal StructureSilica Tetrahedron Special Properties-

Mineral in the mica family are soft silicates: Muscovite and Biotite are minerals that form flat crystals that cleave in only one direction to form thin sheets.

A carbonate is a mineral made of negatively charged carbonate ions bonded to a positive metal ion. Each carbonate is composed of 1 carbon atom and 3 covalently bonded oxygen atoms.

Properties Calcite CaO3 ColorColorless/White LusterGlassy Hardness3 – 3.5 StreakWhite BreakCleavage Density2.7 g/cm 3 Specific Gravity2.7 Crystal StructureRhombohedra Special PropertiesFluorescent Acid TestBubbles

Properties Dolomite CaMg(CO3) ColorWhite LusterGlassy Hardness StreakWhite BreakCleavage Density2.48g/cm 3 Specific Gravity2.8 Crystal StructureRhombohedra Special Properties-

Oxides are any mineral containing significant amounts of iron and oxygen. Sulfides are any mineral containing significant amounts of iron and sulfur. Oxides and sulfides are used in manufacturing to make steel, medicines, cosmetics, plastics, and paints. Any mineral that can be sold for a profit is known as an ore.

PropertiesHematite Fe2O3 Magnetite Fe3O4 Pyrite FeS2 ColorBlack, RedBlack, Brown, GrayPale to Bright Yellow LusterMetallic, EarthyMetallic Hardness – 6.56 – 6.5 StreakRedBlackGreenish Black BreakFracture Conchoidal Density5.255 g/cm g/cm g/cm 3 Specific Gravity5.355 Crystal StructureHexagonalOctahedralCubic Special Properties-Magnetic-

Hematite Magnetite Pyrite