MINERALS

EARTH MATERIALS

CHEMICAL COMPOSITION OF THE LITHOSPHERE

(CRUST ) The Earth’s crust is composed mainly of 8

elements…. oxygen, silicon, aluminum, iron, calcium, sodium, magnesium, & potassium.– These elements exist in minerals, which most

rocks are made of.– Identifying the common minerals is the key to

understanding the composition of the crust.

Average Chemical Compositionof Earth’s Crust

% by mass % by volume

Oxygen (O) 46.10 94.04Silicon (Si) 28.20 0.88Aluminum (Al) 8.23 0.48Iron (Fe) 5.63 0.49Calcium (Ca) 4.15 1.18Sodium (Na) 2.36 1.11Magnesium (Mg) 2.33 0.33Potassium (K) 2.09 1.42

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WHAT ARE MINERALS?

Minerals are made of elements

Minerals are natural Minerals are solids Minerals are inorganic A Minerals’ definite

arrangement of atoms forms crystals

Over 3800 different minerals have been named.

A mineralogist is a scientist that studies minerals

Mineral Formation

1. Minerals form from magma

2. Minerals form from precipitation.

3. Pressure & Temperature

4. Hydrothermal Solutions

MINERALS FROM MAGMA

Magma is molten material beneath Earth’s surface.

Density differences force magma upward. Elements in the magma interact to form minerals. The rate of cooling determines the size of the

mineral crystals. Minerals rich in iron, calcium, & magnesium form

first.Olivine & pyroxene are minerals rich in iron and

magnesium. Sade` was here :D

MINERALS FROM SOLUTION

A solution is a mixture of a solid and a liquid. In nature, when a solution becomes supersaturated

( overfilled ), mineral crystals begin to precipitate or “drop out” of solution.

Minerals can also form when the liquid evaporates from a solution leaving the elements behind to form crystals.

Calcite & Halite are minerals that form in this way.

Hydrothermal Solutions

A hydrothermal solution is a very hot mixture of water & dissolved substances.

When these solutions cool, the dissolved substances combine to form minerals.

Quartz and Pyrite form this way.

MINERAL GROUPS

1. Silicate mineralsa. 96 % of all minerals are silicates.

b. All silicates are made of Oxygen & Silicon joined with other elements.

c. The silica tetrahedron is the main component of all silicate minerals.

d. By sharing oxygen atoms, one tetrahedron can join to another to form chains & sheets.

II. OTHER MINERAL GROUPS

Carbonates – composed of a metal along with the carbonate compound, CO3

Oxides – are minerals of a metal and oxygen.

Other groups include sulfides, sulfates, and halides.

IDENTIFYING MINERALSI. Physical Properties Streak - the color of the mineral’s powder.

– A mineral’s streak is more reliable than color. Luster - the shine of a mineral.

– Metallic vs. Non-metallic luster. Hardness - the ability to cause or resist a

scratch.– Scratches glass or not.

Cleavage - splits easily in one or more direction leaving smooth, flat surfaces.

Fracture – breaks difficultly & unevenly.

Streak

Luster

Metallic Non-metallic

Cleavage

MOHS’ HARDNESS SCALEFrom softest to hardest

1 - Talc 2 - Gypsum 3 - Calcite 4 - Fluorite 5 - Apatite 6 - Feldspar 7 - Quartz 8 - Topaz 9 - Corundum 10 - Diamond

FIELD TEST FOR HARDNESS

ITEM HARDNESS

Thumbnail 2.5

Penny 3.5

Glass plate 5 – 5.5

Iron Nail 6

USES OF MINERALS

D ia m o ndQ u a rtzG a rn e t

C u tt in g ,G rin d in g & A b ra s ives

F e ld sp a r (C e ra m ics )H a lite (S a lt)

G ra p h ite (P e n c ils)

H o u seh o ld Ite m s

B a u x ite (A l)M a g n e tite (F e)

U ra n ite (U )

M e ta ls (O re s)

Q u a rtz

G la ss -m a k ing

Q u a rtzG o ldS ilv e r

E le c tro n ics

E c o no m ic Im p orta n ceo f M in e ra ls