MINERALS AND
MINERAL PROPERTIES
WHAT IS A MINERAL?
Naturally-Occurring
Inorganic
Solid
Crystal Structure
Defined Chemical Composition
WHAT IS A MINERAL?
A mineral MUST have all five characteristics in
order to be considered a mineral.
If not, it is NOT a mineral.
NATURALLY OCCURRING
Means the substance
must be formed by
processes that occur
in the natural world.
Example: Magma
cooling to form Quartz
INORGANIC
Can’t form from materials
that were once part of
living things.
Can’t come from plants,
trees, or animals.
Example: Coal comes
from remains of plants.
Therefore, coal is NOT a
mineral.
SOLID
A mineral is always a
solid, with a definite
volume and shape.
CRYSTAL STRUCTURE
Particles must line up
in a pattern that
repeats over and over
again.
Repeating pattern that
forms a solid is called a
crystal.
DEFINITE CHEMICAL COMPOSITION
Meaning that a mineral
always contains certain
elements.
Example: Diamond is
nothing but carbon
atoms.
Example: Graphite is
nothing but carbon
atoms.
IDENTIFYING MINERALS
Color
Hardness
Streak Color
Crystal Structure
Luster
Cleavage/Fracture
Density
Special Properties
COLOR
Color is an observation based on the color of
the minerals.
Gold
Pyrite
Chalcopyrite
STREAK COLOR
Color of the mineral’s
powder.
Observed by rubbing
mineral against a streak
plate.
***STREAK COLOR AND
MINERAL COLOR CAN
BE DIFFERENT***
LUSTER
Describes how light is reflected from a mineral’s
surface.
6 different types of luster, we only care about 2:
Metallic & Nonmetallic(Dull, Glassy, Silky,
Waxy (Greasy/Pearly), Earthy)
METALLIC LUSTER
Pyrite has a metallic luster.
Bright, shiny.
Looks like a metal.
DULL LUSTER
Graphite has a dull luster.
Not shiny, dull in color.
Hard to describe just by
looking at it.
GLASSY LUSTER
Looks kind of like glass.
Quartz has a glassy luster.
Topaz has a glassy luster.
SILKY LUSTER
Looks and feels sort of
silky.
Does not necessarily feel
like a mineral.
Malachite has a silky
luster.
WAXY(GREASY/PEARLY) LUSTER
Talc has a waxy luster.
Waxy luster kind of feels
like and looks like a
candle.
This is where the waxy
luster comes from.
EARTHY LUSTER
Looks kind of like a rock.
Hematite has an earthy
luster.
DENSITY
Each mineral has a specific density.
No matter the size of the mineral, the density
remains the same.
Density = mass ÷ volume
HARDNESS
1812, Friedrich Mohs,
invented the Mohs
Hardness Scale
Used to test hardness of
minerals.
Hardness determined by a
scratch test.
CRYSTAL STRUCTURE
All minerals have ONE of six crystal structures.
Minerals are grouped based on the type of
crystal structure they have.
CLEAVAGE
Splits easily along a
flat surface.
Calcite is a good
example of cleavage
in minerals!
FRACTURE
Unlike cleavage,
fracture describes
how minerals break
apart in an irregular
way.
SPECIAL PROPERTIES
Magnetic?
Reacts with acid?
Fluorescence?
Some minerals have these special properties!