EARTH’S MATERIALS

Minerals

On the periodic table, of the first 92 elements: 90 are found in the Earth

The crust is the outermost layer of Earth, and includes all continental material and materials that form the ocean bottom.

Extends 10km beneath the continents

Major Elements in the Earth’s crust

Element Percent ( by mass)

Oxygen 46.6%

Silicon 27.7%

Aluminum 8.1%

Iron 5.0%

Calcium 3.6%

Sodium 2.8%

Potassium 2.6%

Magnesium 2.1%

All others 1.5%

What’s a mineral? A mineral is a naturally occurring element of

compound that is inorganic, solid, and has a crystalline structure

Inorganic means that minerals are materials that are not produced by living organisms

The composition of minerals are indicated by their chemical formulaExample: Fluorite= CaF2

Physical Properties

A mineral has a particular chemical composition, although can sometimes vary due to small impurities

Example: Ruby vs. Sapphire

Example

Ruby vs. Sapphire

Both contain corundum, but Ruby has more chromium then Sapphire

Atom Arrangement Some properties are controlled by orderly

arrangement of atoms in a mineral’s structure

This pattern is what makes a mineral crystalline

The arrangement of atoms and the bonds between them can reflect the way a mineral breaks, how hard it is, and what type of crystal shape

How minerals break

Cleavage: the ability of a mineral break along plans that cut across relatively weak chemical bonds, a smooth, flat surface.

Fracture: an irregular break

Hardness

Bonds connecting atoms in materials often have different strengths

When your scratch a mineral with another mineral the scratch forms as bonds in the material are broken.

Mohs Scale of HardnessMost to Least

Talc

Gypsum

Calcite

Fluorite

Apatite

Feldspar

Quartz

Topaz

Corundum

Diamond

Luster and Streak

The way a mineral reflects light is known as lusterMetallicNonmetallic

The color of a mineral in powdered form is called streakThe streak may be the same color as the

mineral