Minerals
What is a mineral?
• Naturally occurring, inorganic solid, with a
specific chemical composition and a definite
crystalline structure
Mineral Characteristics
• Earth’s crust is composed of 3,000 minerals.
• Forming of rocks and shaping Earth’s surface.
• Example: early humans began making tools
from iron.
• Minerals are formed by natural
processes.
• Can not be developed in labs
– Exp: synthetic diamonds
• They are not alive and never were alive.
What’s a mineral and what’s not a mineral?
• Salt is a mineral
• Sugar is not, because its harvested from
plants.
• What about coal?
What’s a mineral and what’s not a mineral?
• Salt is a mineral
• Sugar is not, because its harvested from
plants.
• What about coal?
– No, millions of years ago it formed from organic
materials.
Crystalline structure
• Crystal is a solid which atoms are arranged in
repeating patterns
• A mineral can form in an open space and grow
into a large crystal
Composition of solids
• Each type of mineral has its own unique
chemical composition.
• Some might be specific
– Copper, Silver, and Sulfur are single elements
• others might be complex
– Quartz (SiO2). Combination of 1 Silicon atom and
2 Oxygen atoms.
Rock Forming Minerals
• Of the 3,000 minerals occur in Earth’s crust,
about only 30 are common.
• 8 -10 are rock forming minerals
• Composed of 8 common elements in Earth’s
crust
– Quartz
– Feldspar
– Mica
– Pyroxene
– Amphibole
– Olivine
– Garnet
– Calcite
Minerals from magma
• Magma forms below Earth's surface, and rises
toward the surface because its less dense.
• Magma then cools and crystallizes
• If magma cools slowly, atoms have time to
arrange into large crystals
• If magma reaches water or air and cools
quickly, small crystals form
Minerals from solutions
• Most dissolve in water.
– Such as salts dissolving in the ocean to make it
salty
• Minerals that form from the evaporation of
liquid is called evaporites
Identifying Minerals
• Geologists use several tests to identify
minerals
– Crystal form
– Luster
– Hardness
– Cleavage & Fracture
– Streak
– Color
– Texture
– Density & Specific gravity
– Special properties