Mineral Properties, Uses, and
Identification
Minerals
An inorganic, naturally occurring solid that have a definite
chemical composition, distinctive physical properties and a
crystalline structure.
These are the five things that define a mineral:
• Inorganic
• Naturally Occurring
• Solid
• Definite Crystalline Structure
• Definite Chemical Composition
How many minerals are there??? > 5300 known minerals!
What is the difference between a mineral and a rock?
Physical Properties
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Shape
Luster
Color
Hardness
Streak
Cleavage
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Texture
Magnetism
Specific Gravity
Taste
Odor
Effervesces with HCl
Note: there are more than this that will be very
important to your mineral identification skills should
you choose to take a mineral class later.
Shape: Crystal Habit
Every mineral has a crystal form. The crystal form
is the shape that a crystal will take if it grows
unimpeded and unbroken
Shape: Crystals vs. Granules
• Important : Most mineral specimens are
irregular grains, very few display their
characteristic crystal habit.
HowMineral
many 1
minerals
are
1 Crystal
there?
Mineral 2
Many Crystals
Luster: Metallic vs. Non-Metallic
• Luster: a reflective property of mineral
surfaces.
• Usually we begin by separating the Metallic
and Non-Metallic minerals.
• Minerals can be further divided into subcategories based on luster
• Important: Some minerals exhibit both
metallic and non-metallic properties.
Luster: Metallic
There are two types of metallic minerals:
Metallic and Sub-Metallic.
Luster: Non-Metallic
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Adamantine
Resinous
Glassy/Vitreous
Pearly
Greasy/Oily
Silky
Dull
Earthy
Color
• Wavelengths of visible light are absorbed or
reflected by the mineral
• Some minerals change color or have various
forms of different color
• Sometimes color is determined by trace
elements.
• You cannot rely on color when it comes to
mineral identification.
Hardness
Streak
Color of a powdered mineral which is tested by
rubbing the mineral across a porcelain streak
plate.
Breakage
Cleavage: Tendency of
a mineral to break
along flat planes of
weaker bonding.
• Cleavage Planes 0+
Fracture: Cleavage is
absent and mineral
breaks irregularly
Cleavage
The ability of a mineral to
break or come apart in a
consistent way
• Breakage is along atomic
planes
• Cleavage is consistent
with crystal symmetry
and may be one to multidirectional from one
mineral to another.
• Reported as planes
Cleavage
Cleavage Angles
• Some Minerals have
special cleavages
• Amphiboles
– Hornblende
– 120⁰ and 60 ⁰
• Pyroxenes
– Augite
– 90⁰and 90⁰
Fracture
Describes the inability
of a mineral to break in
a consistent way and
therefore not along
cleavage planes
Conchoidal- a smooth,
curved breakage in all
directions
Other Physical Properties
Magnetism: Some minerals are magnetic. This
ranges from weakly to strongly magnetic.
Specific Gravity: The specific gravity of a material is
a comparison of its weight with the weight of an
equal volume of water. Specific gravity measures
the density of a material.
Taste: Some minerals exhibit a specific taste.
(i.e. Halite and Sylvite)
Odor: Some minerals have a specific smell. (i.e.
sulfur)
Effervesces with HCl: Fizz or give off bubbles.
Mineral Uses
Practice
Sample
#
Hardness Luster
1
Color/
Streak
Color:
green
4
Nonmetallic Streak:
green
Cleavage/
Fracture
Cleavage:
Poor, 0
planes
Fracture:
Good
Other
Properties
Mineral
Name
Slight
fizzing
Malachite
Encrusting
nature
Bright,
distinctive
green