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Physical Properties of Minerals (Other properties (Magnetism (Magnetite),…
Physical Properties of Minerals
Useful for identifying minerals using a systematic method such as Dana classification
Crystal Form and Habit
Since minerals have
definite chemical composition
, it forms
definite structure which crystalizes
into a specific
crystal form
.
Outward appearance of the mineral's crystal form is its habit
.
described as
granular
dendritic
geode
fibrous
reniform
lamellar
prismatic
Cleavage and Fracture
The manner in which a mineral
breaks
is
dependent on its molecular bonding and structure
.
The tendency of a mineral to break along planes of weakness is known as cleavage.
described
number and directions of cleavage planes
quality
Excellent cleavage
smooth, flat and parallel surfaces
Good cleavage
small, smooth, step-like flat surfaces
Poor cleavage
surfaces are
difficult to identify
No cleavage
fracture in an
irregular manner
or as
conchoidal fracture (smooth, curved surfaces)
Luster
Appearance of light
as it is reflected off the mineral's surface
described as
Metallic
polished metal
Nonmetallic
vitreous (like glass)
resinous (like resin)
pearlescent
silky
greasy
earthy
dull
Color and Streak
Color
Most obvious mineral property
Not a reliable feature
for identifying minerals because it
can be altered by chemical impurities within its structure
Quartz
colorless but light impurities can produce a variety of colors
Streak
color of a mineral in its powdered form
obtained by rubbing the mineral on an
abrasive ceramic tile
called
streak plate
Hardness
measurement of the
strength of the chemical bonds
in its structure
measured by scratching it with another mineral or reference mineral with known hardness
Mohs scale of hardness
relative measure of hardness using
common materials
and
standard minerals
to represent a specific hardness value
Density
Specific gravity
measure of the density of a mineral
weight of a mineral relative to the weight of an equal volume of water
common minerals have a specific gravity of
2.7
while gold has 19
Other properties
Magnetism
Magnetite
Taste
Halite is salty
Effervescence/ reaction to acid
calcite and other carbonates will react with weak acid
Feel
Talc is greasy