What are some examples of What are some examples of minerals you see in your minerals you see in your

daily life?daily life?

►Graphite in your pencilGraphite in your pencil►Glass windowsGlass windows

►JewelryJewelry

So what is a mineral?So what is a mineral?

What are the What are the characteristics of all characteristics of all

minerals?minerals?

DefinitionDefinition

►A naturally occurring, A naturally occurring, inorganic solid with specific inorganic solid with specific chemical composition and a chemical composition and a definite crystalline definite crystalline structure.structure.

►Important in forming rocks Important in forming rocks (which we will learn about in (which we will learn about in next unit)next unit)

1. A mineral occurs 1. A mineral occurs naturally.naturally.

2. A mineral is solid 2. A mineral is solid (definite shape and (definite shape and

volume).volume).

3. A mineral has a definite 3. A mineral has a definite chemical composition chemical composition

(element or compound).(element or compound).

4. A mineral’s atoms are 4. A mineral’s atoms are arranged in an orderly arranged in an orderly

pattern (crystal pattern (crystal structure).structure).►Crystal---a solid in which the Crystal---a solid in which the

atoms are arranged in repeating atoms are arranged in repeating patternspatterns

5. A mineral is 5. A mineral is inorganic (was never inorganic (was never

alive).alive).►Is coal a mineral?Is coal a mineral?

Of the almost 4000 known minerals, Of the almost 4000 known minerals, only about 30 are common.only about 30 are common.

The most common are The most common are quartz,feldspar,mica, and quartz,feldspar,mica, and

calcite.calcite.

These minerals make up These minerals make up most of the rocks found most of the rocks found in the Earth’s crust.in the Earth’s crust.

In fact, over In fact, over 60%60% of the of the Earth’s crust is made up Earth’s crust is made up of the family of minerals of the family of minerals

known as feldspar!known as feldspar!

Where Do Minerals Where Do Minerals Come From? Come From?

► Two ways:Two ways: 1. Minerals from Cooling Magma1. Minerals from Cooling Magma

►Magma---molten material found beneath Magma---molten material found beneath Earth’s surfaceEarth’s surface

►Density forces magma upwards into cooler Density forces magma upwards into cooler layers of the Earth, where it coolslayers of the Earth, where it cools

►Compounds interact chemically to form Compounds interact chemically to form mineralsminerals

►Type and amount of elements present Type and amount of elements present determines which mineral will formdetermines which mineral will form

►Rate at which magma cools determines size Rate at which magma cools determines size of mineralof mineral

►If magma cools slowlyIf magma cools slowlylarge large crystals formcrystals form

►If magma cools quicklyIf magma cools quicklysmall small crystals formcrystals form

► 2. Minerals from Solutions2. Minerals from Solutions A given volume of water can only A given volume of water can only dissolve so much solid before it dissolve so much solid before it becomes saturated becomes saturated

A supersaturated solution (overfilled) A supersaturated solution (overfilled) can precipitate mineral crystals can precipitate mineral crystals

Minerals can also form when elements Minerals can also form when elements dissolve in a supersaturated solution dissolve in a supersaturated solution and the liquid evaporates…the elements and the liquid evaporates…the elements remain behind and crystals formremain behind and crystals form

Mineral Mineral IdentificationIdentification

►There are more than 3000 There are more than 3000 minerals, so we need a way minerals, so we need a way

to identify them!to identify them!

To be able to identify these To be able to identify these and other minerals, we need and other minerals, we need to look at the to look at the properties properties

used to separate and used to separate and distinguish these minerals.distinguish these minerals.

Remember!:Remember!:

Rarely is a mineral identified Rarely is a mineral identified by a single property.by a single property.

These properties need to be These properties need to be considered together to considered together to

correctly identify a mineral.correctly identify a mineral.

Color is the most easily Color is the most easily observed mineral observed mineral

property and the property and the leastleast useful! useful!

Some minerals can be found Some minerals can be found in a variety of colors.in a variety of colors.

Some exceptions to the color Some exceptions to the color rule would be rule would be cinnabarcinnabar, , which is always red, and which is always red, and

malachitemalachite, which is green., which is green.

Many minerals have a Many minerals have a similar color.similar color.

Many minerals can turn Many minerals can turn colors due to impurities, colors due to impurities, or they can change colors or they can change colors in various circumstances.in various circumstances.

For example, pure quartz is For example, pure quartz is colorless or white, colorless or white,

impurities can make the impurities can make the mineral rose, purple or pinkmineral rose, purple or pink

►Mass/VolumeMass/Volume►Reflects weight and Reflects weight and

structure (no dependent on structure (no dependent on size or shape)size or shape)

►Common measure of density Common measure of density is specific gravityis specific gravity

Specific gravitySpecific gravity tells you tells you how many times as dense as how many times as dense as

water the mineral is.water the mineral is.

Pure gold can have a specific Pure gold can have a specific gravity as high as 19.3gravity as high as 19.3

IDENTIFYING MINERALS IDENTIFYING MINERALS (Continued)(Continued)

CRYSTAL FORM CRYSTAL FORM ►Takes Luck & Practice Takes Luck & Practice ►Well-formed crystals are Well-formed crystals are uncommon uncommon

►Crystal Classification is Crystal Classification is somewhat subtle somewhat subtle

►Crystals need time, heat, and Crystals need time, heat, and spacespace

The Crystal ClassesThe Crystal Classes

MAJOR MINERAL SUITES MAJOR MINERAL SUITES

ELEMENTSELEMENTS

MetallicMetallic:Au, Ag, Cu :Au, Ag, Cu ►NotNot Al, Pb, Zn, Fe, etc. Al, Pb, Zn, Fe, etc.

Nonmetallic:Nonmetallic: C - Diamond, C - Diamond, Graphite Graphite

►Sulfur Sulfur

MAJOR MINERAL SUITESMAJOR MINERAL SUITES

SULFIDES: Dense, Usually MetallicSULFIDES: Dense, Usually MetallicMany Major OresMany Major Ores

►Pyrite FeSPyrite FeS22

►Chalcopyrite CuFeSChalcopyrite CuFeS22

►Galena PbSGalena PbS►Sphalerite ZnSSphalerite ZnS22

►Molybdenite MoSMolybdenite MoS22

MAJOR MINERAL SUITESMAJOR MINERAL SUITES

HALIDES: Usually Soft, Often HALIDES: Usually Soft, Often SolubleSoluble

►Halite NaCl Halite NaCl ►Fluorite CaFFluorite CaF22

SULFATES: Soft, Light ColorSULFATES: Soft, Light Color►Gypsum CaSOGypsum CaSO4 4

►Barite BaSOBarite BaSO44

MAJOR MINERAL SUITESMAJOR MINERAL SUITES

OXIDES: Often Variable, Some OresOXIDES: Often Variable, Some Ores►Hematite FeHematite Fe22OO33 ►Bauxite Al(OH) Bauxite Al(OH) 33 (a hydroxide) (a hydroxide) ►Corundum AlCorundum Al22OO33 (Ruby, Sapphire) (Ruby, Sapphire) CARBONATES: Fizz in Acid, Give CARBONATES: Fizz in Acid, Give off COoff CO22

►Calcite CaCOCalcite CaCO33

►Dolomite CaMg (CODolomite CaMg (CO33))22

MOST IMPORTANT MINERAL MOST IMPORTANT MINERAL SUITE: SUITE:

The Silicate Minerals The Silicate Minerals ►Si + O = 75% of Crust Si + O = 75% of Crust ►Silicates make up 95% + of all Silicates make up 95% + of all Rocks Rocks

►SiOSiO44: -4 charge : -4 charge

►Link Corner-To-Corner by Sharing Link Corner-To-Corner by Sharing Oxygen atoms Oxygen atoms

Luster refers to the way a Luster refers to the way a mineral reflects light from mineral reflects light from

its surface.its surface.

Notice the difference between Notice the difference between these two minerals?these two minerals?

The mineral on the left The mineral on the left has a has a metallic lustermetallic luster, , the one on the right, a the one on the right, a

nonmetallic lusternonmetallic luster..

Metallic vs. Metallic vs. NonmetallicNonmetallic

►Metallic---shiny surfaces that Metallic---shiny surfaces that reflect light like the chrome reflect light like the chrome trim on carstrim on cars Silver, gold, copper, galenaSilver, gold, copper, galena

►Nonmetallic---do not shine Nonmetallic---do not shine (dull, pearly, waxy, silky)(dull, pearly, waxy, silky) Calcite, gypsum, sulfur, quartzCalcite, gypsum, sulfur, quartz

There are several terms used There are several terms used to describe nonmetallic to describe nonmetallic luster. Examples could be luster. Examples could be

vitreousvitreous, like the quartz on , like the quartz on the left, or the left, or pearlypearly, like the , like the

gypsum on the right.gypsum on the right.

Other terms that might be Other terms that might be used include used include greasy, dull, greasy, dull,

and and earthyearthy..

Can you tell which of these Can you tell which of these has an earthy luster?has an earthy luster?

►Describes how a mineral Describes how a mineral feelsfeels

►Examples: smooth, rough, Examples: smooth, rough, ragged, greasy, soapy, glassyragged, greasy, soapy, glassy

StreakStreak of a mineral is the of a mineral is the color of its powder when color of its powder when rubbed on an unglazed rubbed on an unglazed

white tile.white tile.

The streak is often not the The streak is often not the same color as the mineral. same color as the mineral.

A minerals color may vary, A minerals color may vary, but the streak rarely but the streak rarely

will!will!

►One of the main tests used to One of the main tests used to distinguish pyrite (fool’s gold) distinguish pyrite (fool’s gold) from gold.from gold.

►Pyrite leaves a greenish-black Pyrite leaves a greenish-black streak and gold leaves a yellow streak and gold leaves a yellow streak.streak.

The The cleavage cleavage of a mineral is of a mineral is its tendency to split easily its tendency to split easily or to separate along flat or to separate along flat

surfaces.surfaces.

Cleavage can even be observed Cleavage can even be observed on tiny mineral grains on tiny mineral grains making it a very useful making it a very useful

property!property!

MicaMica is probably the best is probably the best example as it splits into example as it splits into thin sheets. It is said to thin sheets. It is said to have one perfect cleavage.have one perfect cleavage.

FeldsparFeldspar splits readily in splits readily in two directions, always at two directions, always at or near right angles.or near right angles.

CalciteCalcite and and galenagalena cleave in cleave in three directions.three directions.

They are said to have three good They are said to have three good cleavages.cleavages.

Not all minerals show cleavage.Not all minerals show cleavage.

Those that don’t break along Those that don’t break along cleavage surfaces are said to cleavage surfaces are said to

have have fracturefracture..

The The hardnesshardness of a mineral is a of a mineral is a measure of how easily it can be measure of how easily it can be

scratched.scratched.

Diamond is the hardest of all Diamond is the hardest of all minerals, and talc is the softest.minerals, and talc is the softest.

Friedrich Friedrich MohsMohs devised a hardness devised a hardness scale. scale.

In this scale, ten well known In this scale, ten well known minerals are given numbers from one minerals are given numbers from one

to ten.to ten.Lets take a look at the ten minerals Lets take a look at the ten minerals used and some of the simple tests.used and some of the simple tests.

Moh’s Hardness ScaleMoh’s Hardness Scale

Talc Talc (left) is the softest and (left) is the softest and has a hardness of 1. A soft has a hardness of 1. A soft

pencil lead will scratch talc.pencil lead will scratch talc.GypsumGypsum is a bit harder and has is a bit harder and has a hardness of 2. A fingernail a hardness of 2. A fingernail

scratches gypsum.scratches gypsum.

CalciteCalcite (left) has a hardness of 3 (left) has a hardness of 3 and a copper penny just scratches and a copper penny just scratches

it.it.FluoriteFluorite has a hardness of 4 and has a hardness of 4 and it can be scratched by an iron or it can be scratched by an iron or

brass nail.brass nail.

ApatiteApatite (left) has a hardness of (left) has a hardness of 5 and can be scratched by a 5 and can be scratched by a

steel knife blade.steel knife blade.FeldsparFeldspar has a hardness of 6 and has a hardness of 6 and it will scratch a window glass.it will scratch a window glass.

QuartzQuartz (left), with a hardness (left), with a hardness of 7, is the hardest of the of 7, is the hardest of the common minerals. It easily common minerals. It easily

scratches hard glass and steel.scratches hard glass and steel.TopazTopaz has a hardness of 8 and has a hardness of 8 and

will scratch quartz.will scratch quartz.

CorundumCorundum (left) has a hardness of (left) has a hardness of 9. Corundum will scratch topaz.9. Corundum will scratch topaz.DiamondDiamond with its hardness of 10 with its hardness of 10 can easily scratch the rest of can easily scratch the rest of

the minerals. the minerals.

Malleable

Magnetic

Radioactive

Flourescence

Taste

CalciteCalcite is calcium carbonate, is calcium carbonate, CaCOCaCO33. If a drop of weak . If a drop of weak

hydrochloric acid is placed hydrochloric acid is placed on calcite, the acid bubbles on calcite, the acid bubbles

as carbon dioxide is as carbon dioxide is released.released.

Minerals that can be hammered Minerals that can be hammered thin or shaped are said to thin or shaped are said to show these properties.show these properties.

Can you think of a mineral that Can you think of a mineral that might be shaped or hammered?might be shaped or hammered?

GoldGold would be a perfect would be a perfect example!example!

Some minerals Some minerals that contain that contain Iron, are Iron, are

magnetic and magnetic and can be picked can be picked

up by a up by a magnet.magnet.

This is the state This is the state of glowing while of glowing while

under a under a ultraviolet ultraviolet

light.light.

Some minerals even Some minerals even glow once the glow once the

light is turned light is turned off!off!

Some minerals, Some minerals, such as this such as this uraniniteuraninite, are , are radioactive.radioactive.

They give off They give off subatomic subatomic particles.particles.

HaliteHalite (rock (rock salt) can be salt) can be identified by identified by its taste.its taste.

This practice This practice is not is not

recommendedrecommended

►You sit on minerals, wear them, You sit on minerals, wear them, and even eat them!and even eat them!

►They are everywhere!They are everywhere!►Used to make computers, cars, Used to make computers, cars, televisions, desks, roads, televisions, desks, roads, buildings, jewelry, beds, buildings, jewelry, beds, paints, sports equipment, and paints, sports equipment, and medicines.medicines.

OresOres►A mineral that contains a useful A mineral that contains a useful substance that can be mined at a substance that can be mined at a profitprofit

►Hematite is an ore that contains Hematite is an ore that contains the element ironthe element iron

►Aluminum is found in the ore Aluminum is found in the ore bauxitebauxite

►Titanium is found in the ore Titanium is found in the ore rutilerutile

MinesMines►Ores that are found deep in the Ores that are found deep in the Earth’s crust are removed by Earth’s crust are removed by miningmining

►Ores near the surface are Ores near the surface are removed by open-pit miningremoved by open-pit mining

GemsGems►Gems are valuable minerals that are Gems are valuable minerals that are prized for their rarity and beautyprized for their rarity and beauty

►Rubies, emeralds, and diamonds are Rubies, emeralds, and diamonds are cut, polished, and used for jewelrycut, polished, and used for jewelry

►Trace elements can make one variety Trace elements can make one variety of a mineral more colorful and more of a mineral more colorful and more prizedprized Amethyst is the gem form of quartzAmethyst is the gem form of quartz Rubies and sapphires are the gem forms Rubies and sapphires are the gem forms of corundum of corundum