3. A mineral has a definite chemical3. A mineral has a definite chemical
4. A mineral’s atoms are arranged4. A mineral’s atoms are arranged
in an orderly pattern.in an orderly pattern.
5. A mineral is inorganic (was never5. A mineral is inorganic (was never
Approximately 4000 known mineralsApproximately 4000 known minerals
About 30 are commonAbout 30 are common
The most common areThe most common are
quartz,feldspar,mica, and calcite.quartz,feldspar,mica, and calcite.
These minerals make up most ofThese minerals make up most of
the rocks found in the Earth’sthe rocks found in the Earth’s
In fact, overIn fact, over 60%60% of the Earth’sof the Earth’s
crust is made up of the family ofcrust is made up of the family of
minerals known as feldspar!minerals known as feldspar!
To be able to identify these andTo be able to identify these and
other minerals, we need to look atother minerals, we need to look at
thethe propertiesproperties used to separateused to separate
and distinguish these minerals.and distinguish these minerals.
Rarely is a mineral identified by aRarely is a mineral identified by a
single property.single property.
These properties need to beThese properties need to be
considered together to correctlyconsidered together to correctly
identify a mineral.identify a mineral.
Color is the most easily observedColor is the most easily observed
mineral property and themineral property and the leastleast
Many minerals have a similarMany minerals have a similar
Many minerals can turn colors dueMany minerals can turn colors due
to impurities, or they can changeto impurities, or they can change
colors in various circumstances.colors in various circumstances.
For example, pure quartz is colorlessFor example, pure quartz is colorless
or white, impurities can make theor white, impurities can make the
mineral rose, purple or pink!mineral rose, purple or pink!
Some exceptions to the color ruleSome exceptions to the color rule
would bewould be cinnabarcinnabar, which is, which is
always red, andalways red, and malachitemalachite, which, which
is green.is green.
Discuss the following!Discuss the following!
How many of the characteristicsHow many of the characteristics
of minerals can you name?of minerals can you name?
Why isn’t color a very goodWhy isn’t color a very good
property to identify mostproperty to identify most
Luster refers to the way a mineralLuster refers to the way a mineral
shines in reflected light.shines in reflected light.
Notice the difference betweenNotice the difference between
these two minerals?these two minerals?
The mineral on the left has aThe mineral on the left has a
metallic lustermetallic luster, the one on the, the one on the
right, aright, a nonmetallic lusternonmetallic luster..
There are several terms used toThere are several terms used to
describe nonmetallic luster. Examplesdescribe nonmetallic luster. Examples
could becould be vitreousvitreous, like the quartz on, like the quartz on
the left, orthe left, or pearlypearly, like the gypsum on, like the gypsum on
the right.the right.
Other terms that might be used includeOther terms that might be used include
greasy, dull,greasy, dull, andand earthyearthy..
Can you tell which of these has anCan you tell which of these has an
earthy luster and which has a vitreousearthy luster and which has a vitreous
StreakStreak of a mineral is the color of itsof a mineral is the color of its
powder when rubbed on anpowder when rubbed on an
unglazed white tile.unglazed white tile.
The streak is often not the sameThe streak is often not the same
color as the mineral.color as the mineral.
A minerals color may vary, but theA minerals color may vary, but the
streak rarely will!streak rarely will!
TheThe cleavagecleavage of a mineral is itsof a mineral is its
tendency to split easily or totendency to split easily or to
separate along flat surfaces.separate along flat surfaces.
Cleavage can even be observed onCleavage can even be observed on
tiny mineral grains making it a verytiny mineral grains making it a very
useful property!useful property!
MicaMica is probably the best example asis probably the best example as
it splits into thin sheets. It is said toit splits into thin sheets. It is said to
have one perfect cleavage.have one perfect cleavage.
FeldsparFeldspar splits readily in twosplits readily in two
directions, always at or near rightdirections, always at or near right
CalciteCalcite andand galenagalena cleave in threecleave in three
They are said to have three goodThey are said to have three good
Not all minerals show cleavage.Not all minerals show cleavage.
Those that don’t break along cleavageThose that don’t break along cleavage
surfaces are said to havesurfaces are said to have fracturefracture..
Discuss the following!Discuss the following!
There are four common minerals,There are four common minerals,
how many can you name?how many can you name?
Of the four common minerals,Of the four common minerals,
which one makes up over 60% ofwhich one makes up over 60% of
the Earth’s crust?the Earth’s crust?
TheThe hardnesshardness of a mineral is itsof a mineral is its
resistance to being scratched.resistance to being scratched.
Diamond is the hardest of allDiamond is the hardest of all
minerals, and talc is the softest.minerals, and talc is the softest.
FriedrichFriedrich MohsMohs devised a hardness scale.devised a hardness scale.
In this scale, ten well-known minerals areIn this scale, ten well-known minerals are
given numbers from one to ten.given numbers from one to ten.
Lets take a look at the ten minerals usedLets take a look at the ten minerals used
and some of the simple tests.and some of the simple tests.
TalcTalc (left) is the softest and has a hardness(left) is the softest and has a hardness
of 1. A soft pencil lead will scratch talc.of 1. A soft pencil lead will scratch talc.
GypsumGypsum is a bit harder and has a hardnessis a bit harder and has a hardness
of 2. A fingernail scratches gypsum.of 2. A fingernail scratches gypsum.
CalciteCalcite (left) has a hardness of 3 and a(left) has a hardness of 3 and a
copper penny just scratches it.copper penny just scratches it.
FluoriteFluorite has a hardness of 4 and it canhas a hardness of 4 and it can
be scratched by an iron or brass nail.be scratched by an iron or brass nail.
ApatiteApatite (left) has a hardness of 5 and(left) has a hardness of 5 and
can be scratched by a steel knifecan be scratched by a steel knife
FeldsparFeldspar has a hardness of 6 and it willhas a hardness of 6 and it will
scratch a window glass.scratch a window glass.
QuartzQuartz (left), with a hardness of 7, is the(left), with a hardness of 7, is the
hardest of the common minerals. It easilyhardest of the common minerals. It easily
scratches hard glass and steel.scratches hard glass and steel.
TopazTopaz has a hardness of 8 and will scratchhas a hardness of 8 and will scratch
CorundumCorundum (left) has a hardness of 9.(left) has a hardness of 9.
Corundum will scratch topaz.Corundum will scratch topaz.
DiamondDiamond with its hardness of 10 can easilywith its hardness of 10 can easily
scratch the rest of the minerals.scratch the rest of the minerals.
Discuss the following!Discuss the following!
Does this mineral show cleavageDoes this mineral show cleavage
or fracture?or fracture?
Of the four most commonOf the four most common
minerals, which is the highestminerals, which is the highest
Crystal shapeCrystal shape can be a usefulcan be a useful
property to identify minerals if theproperty to identify minerals if the
minerals have had the time andminerals have had the time and
space to form crystals. Mostspace to form crystals. Most
mineral grains that are found inmineral grains that are found in
rocks, lack the room to grow.rocks, lack the room to grow.
Specific gravitySpecific gravity tells you how manytells you how many
times as dense as water the mineraltimes as dense as water the mineral
Pure gold can have a specific gravityPure gold can have a specific gravity
as high as 19.3!as high as 19.3!
CalciteCalcite is calcium carbonate, CaCOis calcium carbonate, CaCO33..
If a drop of weak hydrochloric acidIf a drop of weak hydrochloric acid
is placed on calcite, the acidis placed on calcite, the acid
bubbles as carbon dioxide isbubbles as carbon dioxide is
Minerals that can be hammered thin orMinerals that can be hammered thin or
shaped are said to show theseshaped are said to show these
Can you think of a mineral that might beCan you think of a mineral that might be
shaped or hammered?shaped or hammered?
GoldGold would be a perfect example!would be a perfect example!
Some mineralsSome minerals
that contain Iron,that contain Iron,
are magnetic andare magnetic and
can be picked upcan be picked up
by a magnet.by a magnet.
This is the state ofThis is the state of
glowing while under aglowing while under a
ultraviolet light.ultraviolet light.
Some minerals evenSome minerals even
glow once the light isglow once the light is
turned off!turned off!
Some minerals, suchSome minerals, such
as thisas this uraniniteuraninite, are, are
They give offThey give off
subatomic particlessubatomic particles
that will activate athat will activate a
Geiger counterGeiger counter..
HaliteHalite (rock salt)(rock salt)
can be identifiedcan be identified
by its taste.by its taste.
This practice is notThis practice is not