1. A mineral occurs naturally 2. A mineral is solid (definite shape & volume). It’s a crystalline structure.

1. A mineral occurs 1. A mineral occurs naturallynaturally

2. A mineral is 2. A mineral is solidsolid (definite (definite shape & volume). Itshape & volume). It’’s a s a

crystalline structure.crystalline structure.

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

(combines several atoms).(combines several atoms).

4. A mineral4. A mineral’’s atoms are s atoms are arranged in arranged in repeating patterns repeating patterns

(Crystal).(Crystal).

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

MagmaMagma►Minerals can form from the cooling of Minerals can form from the cooling of

magma.magma.

►MagmaMagma is molten material found is molten material found beneath Earth’s surface.beneath Earth’s surface.

Minerals from SolutionMinerals from Solution

►Minerals can form from a Minerals can form from a supersaturated solution.supersaturated solution.

►For example: Gypsum deposits can For example: Gypsum deposits can form from the evaporation of water.form from the evaporation of water.

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 calcitequartz,feldspar,mica, and calcite..

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

SilicatesSilicates

►Minerals that contain both O and Si Minerals that contain both O and Si and one or more other elements are and one or more other elements are known as known as silicatessilicates..

►Make up 96% of the minerals in the Make up 96% of the minerals in the Earth’s crust.Earth’s crust.

►Example: Feldspar and QuartzExample: Feldspar and Quartz

CarbonatesCarbonates

►Minerals composed of one or more metallic Minerals composed of one or more metallic elements with the carbonate compound COelements with the carbonate compound CO3.3.

►Examples: Calcite, dolomite, and Examples: Calcite, dolomite, and rhodochrosite.rhodochrosite.

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 used to separate and distinguish these separate and distinguish these

minerals.minerals.

OxidesOxides

►Compounds of oxygen and a metal.Compounds of oxygen and a metal.

Minerals are Minerals are identified by several identified by several

propertiesproperties!!

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.

Discuss the following with a Discuss the following with a neighbor!neighbor!

How many of the characteristics How many of the characteristics of minerals can you name?of minerals can you name?

Why isnWhy isn’’t color a very good 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.

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

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

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

an unglazed white tile.an unglazed white tile.

The streak is often not the same The streak is often not the same color as the mineral. 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 observed Cleavage can even be observed on tiny mineral grains making on tiny mineral grains making

it a very useful property!it a very useful 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.

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

Those that donThose that don’’t break along cleavage t break along cleavage surfaces are said to have surfaces are said to have fracturefracture..

Discuss the following with a Discuss the following with a neighbor!neighbor!

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% which one makes up over 60%

of the Earthof the Earth’’s crust?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 well known minerals In this scale, ten well known 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.

The Mohs Hardness scale ranks The Mohs Hardness scale ranks from most likely to be scratched from most likely to be scratched (1) to least likely to be scratched (1) to least likely to be scratched

(10).(10).

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

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

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

the mineral is.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.

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!

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

identified by its identified by its taste.taste.

This practice is This practice is not not

recommended!recommended!

OresOres►A mineral is an ore if it contains a A mineral is an ore if it contains a

useful substance that can be mined at useful substance that can be mined at a profit.a profit.

►Look around the room, are any items Look around the room, are any items made of iron? If so, their original made of iron? If so, their original source may have been hematite.source may have been hematite.

Items that contain ironItems that contain iron

Ores Continued…Ores Continued…

►Ores located deep with Earth’s crust Ores located deep with Earth’s crust are removed by underground mining.are removed by underground mining.

►Ores that are near Earth’s surface are Ores that are near Earth’s surface are obtained from large, open-pit mines.obtained from large, open-pit mines.

GemsGems►What makes a ruby more valuable What makes a ruby more valuable

than mica?than mica?

►Rubies are much rarer and more Rubies are much rarer and more visually pleasing than mica.visually pleasing than mica.

►Rubies thus are considered GEMS.Rubies thus are considered GEMS.

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

Examples of GemsExamples of Gems

DiamondsDiamonds EmeraldsEmeralds