AtomsAtoms

Atoms – basic building blocks for all Atoms – basic building blocks for all earth materials; consist of 3 basic earth materials; consist of 3 basic components: protons, neutrons, components: protons, neutrons, electronselectrons

Atoms combine to form Atoms combine to form ElementsElements

ElementsElements – fundamental component – fundamental component that can not be broken down into that can not be broken down into other substances by ordinary other substances by ordinary chemical processeschemical processes

Elements combine to form Elements combine to form mineralsminerals

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

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

minerals?minerals?

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

2. A mineral is solid.2. A mineral is solid.

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

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

pattern.pattern.

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

General Facts About General Facts About MineralsMinerals

Around 4,000 minerals have been Around 4,000 minerals have been identifiedidentified

A few are “native elements” -- made of A few are “native elements” -- made of only one element, such as sulfur, gold. only one element, such as sulfur, gold. copper, and graphite (carbon)copper, and graphite (carbon)

Most are compounds, especially the Most are compounds, especially the silicate group (Si, O).silicate group (Si, O).

Other important groups are oxides, Other important groups are oxides, carbonates, and sulfides.carbonates, and sulfides.

Gold (Au)Silver (Ag)Platinum (Pt)Diamond (C)Graphite (C)Sulfur (S)Copper (Cu)

MINERALS

NATIVE ELEMENTS

Copper

Silver

Gold

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

These minerals make up most These minerals make up most of the rocks found in the of the rocks found in the

Earth’s crust.Earth’s crust.

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

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

at the at the properties properties used to separate used to separate and distinguish these minerals.and 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 property observed mineral property

and the and the leastleast useful! useful!

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, impurities colorless or white, impurities can make the mineral rose, can make the mineral rose,

purple or pink!purple or pink!

Discuss the following!Discuss the following!

How many of the How many of the characteristics of minerals characteristics of minerals

can you name?can you name?

Why isn’t color a very good Why isn’t color a very good property to identify most property to identify most

minerals?minerals?

Luster refers to the way a Luster refers to the way a mineral shines in reflected mineral shines in reflected

light.light.Notice the difference between Notice the difference between

these two minerals?these two minerals?

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

on the right, a on the right, a nonmetallic nonmetallic lusterluster..

There are several terms used to There are several terms used to describe nonmetallic luster. describe nonmetallic luster.

Examples could be Examples could be vitreousvitreous, like , like the quartz on the left, or the quartz on the left, or pearlypearly, ,

like the gypsum on the right.like the gypsum on the right.

Other terms that might be used Other terms that might be used include include greasy, dull, greasy, dull, and and earthyearthy..

Can you tell which of these has an Can you tell which of these has an earthy luster and which has a earthy luster and which has a

vitreous luster?vitreous luster?

Earthy

Vitreous

StreakStreak of a mineral is the color of a mineral is the color of its powder when rubbed of its powder when rubbed on an unglazed white tile.on an unglazed 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, but A minerals color may vary, but the streak rarely will!the streak rarely will!

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

Cleavage can even be Cleavage can even be observed on tiny mineral observed on tiny mineral

grains making it a very useful grains making it a very useful property!property!

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

perfect cleavage.perfect cleavage.

FeldsparFeldspar splits readily in two splits readily in two directions, always at or near directions, always at or near

right angles.right angles.

CalciteCalcite and and galenagalena cleave in three cleave in three directions.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 cleavage Those that don’t break along cleavage

surfaces are said to have surfaces are said to have fracturefracture..

IdentifyIdentify thethe mineralsminerals belowbelow forfor cleavagecleavage andand fracturefracture

CLEAVAGECLEAVAGE FRACTUREFRACTURE

in

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% of which one makes up over 60% of

the Earth’s crust?the Earth’s crust?

The The hardnesshardness of a mineral is its of a mineral is its resistance to being scratched.resistance to being 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 wellknown minerals In this scale, ten wellknown minerals are given numbers from one to ten.are given numbers from one 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.

MohsMohs hardness scale hardness scale

Hardest10. Diamond 4. Fluorite9. Corundum 3. Calcite8. Topaz 2. Gypsum7. Quartz 1. Talc6. Potassium Feldspar Softest5. Apatite

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

scratch talc.scratch talc.GypsumGypsum is a bit harder and has a is a bit harder and has a

hardness of 2. A fingernail scratches hardness of 2. A fingernail scratches gypsum.gypsum.

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

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

brass nail.brass nail.

ApatiteApatite (left) has a hardness of 5 and (left) has a hardness of 5 and can be scratched by a steel knife blade.can be scratched by a steel knife blade.FeldsparFeldspar has a hardness of 6 and it will has a hardness of 6 and it will

scratch a window glass.scratch a window glass.

QuartzQuartz (left), with a hardness of 7, (left), with a hardness of 7, is the hardest of the common is the hardest of the common

minerals. It easily scratches hard minerals. It easily scratches hard glass and steel.glass and steel.

TopazTopaz has a hardness of 8 and will has a hardness of 8 and will scratch quartz.scratch quartz.

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 with its hardness of 10 can easily scratch the rest of the easily scratch the rest of the

minerals. minerals.

Absolute HardnessAbsolute Hardness1 1 TalcTalc 72 72 OrthoclaseOrthoclase 3 3 GypsumGypsum 100 100 QuartzQuartz 9 9 CalciteCalcite 200 200 TopazTopaz

21 21 FluoriteFluorite 400 400 CorundumCorundum 48 48 ApatiteApatite 1600 1600 DiamondDiamond

Discuss the following!Discuss the following!

Does this mineral show Does this mineral show cleavage or fracture?cleavage or fracture?

Of the four most common Of the four most common minerals, which is the minerals, which is the

highest hardness?highest hardness?

Crystal shapeCrystal shape can be a useful can be a useful property to identify minerals if property to identify minerals if the minerals have had the time the minerals have had the time

and space to form crystals. Most and space to form crystals. Most mineral grains that are found in mineral grains that are found in

rocks, lack the room to grow.rocks, lack the room to grow.

Specific gravitySpecific gravity tells you how tells you how many times as dense as 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 19.3!gravity as high as 19.3!

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

hydrochloric acid is placed on hydrochloric acid is placed on calcite, the acid bubbles as calcite, the acid bubbles as carbon dioxide is released.carbon dioxide is released.

Malleable

Magnetic

Radioactive

Flourescence

Taste

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

these properties.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 magnet.up by a magnet.

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

under a ultraviolet under a ultraviolet light.light.

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

light is turned off!light is turned off!

Some minerals, such Some minerals, such as this as this uraniniteuraninite, , are radioactive.are radioactive.They give off They give off

subatomic subatomic particles that will particles that will activate a activate a Geiger Geiger

countercounter..

HaliteHalite (rock salt) (rock salt) can be identified can be identified

by its taste.by its taste.This practice is This practice is

not not recommended!recommended!