Minerals are naturally-occurring solids that have a crystal structure, are inorganic,  and have a definite chemical composition.
Naturally-occurring- not man-made
Solid- keeps its shape
Crystal-repeating pattern of shapes in the particles
Inorganic- not made of living things
Definite chemical composition- contains elements in definite proportions
uHave a repeating pattern of particles
uHave flat sides (faces)
uHave sharp edges and corners


Quartz Often Exhibits Good Crystal Form.
Definite Composition
Substance composed of one kind of atom. Atoms are
the smallest particles of an element. Elements are the basic building blocks of minerals.
Two or more elements combined.
What are minerals and what are their characteristics?
Properties of Minerals
u Hardness is a measure of the resistance of a mineral to being scratched.
u Mohs scale consists of 10 minerals arranged from 10 (hardest) to 1 (softest).
Mohs Scale of Hardness

Mohs Hardness Scale

Number - Description - Example Mineral

1 - rubs off on fingers - talc

2 - can be scratched by fingernail - gypsum

3 - can be scratched by a copper penny - calcite

4 - can be scratched by a steel nail - fluorite

5 - can be scratched by a steel nail - apatite

6 - scratches glass - feldspar

7 - scratches steel or glass - quartz

8 - scratches quartz - topaz

9 - scratches topaz - corundum

10 - scratches all materials - diamond


u Small amounts of different elements can give the same mineral different colors.
u Streak is the color of a mineral in its powdered form.
u Luster is used to describe how light is reflected from the surface of a mineral.
Pyrite (Fool’s Gold) Displays
Metallic Luster.

u Density is mass per volume.
Crystal Systems

uu The pattern of how the crystals are arranged.

uu There are six different crystal systems

u Cleavage is the tendency of a mineral to cleave, or break, along flat, even surfaces.
Mica Has Cleavage in One Direction

u Minerals that do not show cleavage when broken are said to fracture.
u Fracture—the uneven breakage of a mineral
Special properties
u Magnetic
u Fluorescent
u Electrical 
u Radioactive
How Minerals Form
1. Crystallization from magma
  • As magma cools inside the crust (or as lava cools on the surface), minerals form.
  • Fast cooling: smaller crystals
  • Slower cooling: larger crystals
Minerals Formed as a Result of Crystallization of Magma

2. Crystallization of materials dissolved in water 
  • Magma heats water beneath the surface.
  • This water is solution containing many elements. As hot water from beneath the surface cools, the elements crystalize into minerals.
3. Crystallization from evaporation
  • As oceans and seas have evaporated, they have left deposits of crystals.

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