Minerals

Matter

• Anything that takes up space and has mass.

Physical Properties: characteristics that can be observed with out changing the composition of the substance.

Chemical Properties: characteristics that describe what a substance is composed of and how it will react with other substances

Elements

• A substance that has a characteristic set of physical and chemical properties.

Elements consist of atoms

• Atom: the smallest unit of an element that has all the properties of that element.

Minerals

• Occur naturally• Inorganic• Crystalline• Solid

Determining if something can be a mineral……

Ask 4 basic questions1. Is the substance inorganic?2. Does it occur naturally?3. Is the substance a solid in crystalline form?4. Does it have a definite chemical composition?

If the answer is YES to all 4 questions, then it is a mineral.

There are over 3,000 minerals!!!!

• The 20 common minerals are called the rock forming minerals• 10 of these make up 90% of Earth’s crust

Two Main Groups of Minerals

1. Silicate Minerals– Contain atoms of silicon (Si) and oxygen (O)– Make up 96% of Earth’s crust– Feldspar: metal combined with Si and O

2. Nonsilicate Minerals– Minerals that do not contain Silicon (Si)– Make up 4 % of the crust– 6 major groups

Are these silicate or nonsilicate minerals?

Crystalline Structure of Minerals

• A specific geometric arrangement of atoms• Crystal: Natural solid with a definite internal

pattern

How are crystal shapes studied?

• X-rays

Crystalline structure of silicate minerals

9.2 Identifying Minerals

• Scientists that study minerals are called mineralogists

• Journal: Why do you think studying minerals might be important?

Characteristics of minerals

• Color• Luster• Streak• Cleavage/Fracture• Hardness• Crystal Shape• Density

Color

• Easily observed • Unreliable

Luster

• The ability to reflect light– Metallic: Ability to reflect light– Nonmetallic • Glassy (transparent)• Waxy• Pearly• Brilliant• Dull (earthy)

Streak

• Color of mineral in powder form• Use an unglazed ceramic tile called a streak

plate

How a mineral splits apart when broken… • Cleavage: When a mineral splits easily along a

plane

• Fracture: Break in uneven, curved, irregular patterns

Cleavage and Fracture

Hardness• The measure of a mineral’s ability to resist

scratching• Measured using the Measure of Hardness

Scale (MOHS)

What is the hardness of a mineral that can scratch quartz but is scratched by Topaz?

Crystal Shape

Density

• Ratio of mass to volume of a substance

D = m/v• Units of measure: g/cm3

Special Properties of Minerals

• Magnetism• Fluorescence• Phosphorescence• Double Refraction• Radioactivity

Magnetism

• Attract small particles of iron due to magnetically aligned poles.

• Fluorescence: Ability to glow under UV light• Phosphorescence: Ability to continue glowing

after UV light source is removes

RefractionRefraction• Refraction: Bending of light rays as they pass

through different materials• Double refraction: Light rays split into two

parts

Radioactivity

• When an unstable nucleus of an element releases a particle

Density Lab