Introduction to Minerals

What are minerals?What characteristics do all minerals

share? What roles have minerals played in

our civilization?Where do minerals come from and

what are the processes by which minerals form?

What are the major groups of minerals?

Minerals are a type of matter and we know that all matter is made of?

But more specifically, a minerals must meet five criteria to be called a mineral…

atoms.

All Minerals are…

SOLIDWhich of the following could be a mineral?

All minerals are

Inorganic= were never alive

Which of the following could be a mineral?

Inorganic- was never alive

Organic- is currently alive

All minerals occur naturally.

•If that is true, which of the following is not made of minerals?

All minerals have a definite chemical composition.

This means that in each individual mineral, certain types of atoms will come together (bond) in certain ways

Ex. this is similar to how 2 hydrogen's and one oxygen come together to form the most important molecule on Earth!

O

HH

The atoms in minerals are arranged into orderly structures called crystals.

- Cubic- Tetragonal- Orthorhombic- Hexagonal

A huge portion of Earth is made of minerals.

Most rocks are a combination of minerals.

Minerals provide nutrients to living things (like us) that allow us to live and thrive.

Many of the things we use every day are manufactured using minerals.

Can you think of any examples?

Minerals and Rocks

Coal

Scoria

Gneiss

***You should see lots of different minerals in every single rock

Minerals are individual crystals

of all the same stuff

Rocks are combinations of minerals

Amethyst Calcite Garnet

Galena Gold Pyrite

***Notice how each is one single type of crystal!

Mineral crystals can form in two ways:

From stuffdissolved in liquids

(Evaporation & Hot Water)

From Cooling Magma & Lava

Intrusive Cooling:Magma cools slowly

(Long Time = Large Crystals)

Extrusive Cooling:Lava cools Fast

(Short Time = Small Crystals)

Minerals form from hot magma as it cools inside the crust, or as lava hardens on the surface.

When these liquids cool to a solid state, they form crystals.

Size of the crystal depends on time it takes to cool down.

RhyoliteGranite

When the hot material cools fast, it has smaller crystal size. When it cools slowly, it

has large crystals.You can see

individual crystals in Granite

=cooled slowly

You can’t see many individual crystals in Rhyolite

=cooled very fast

Some minerals form when solutions/mixtures evaporate.

When water evaporates, it leaves behind the stuff that’s dissolved in it.

The longer it takes to evaporate, the larger the crystal.

i.e. salt & water – ocean, Halite, Gypsum, Calcite.

**All the white stuff = salt mineral crystals that formed when the water of this lake evaporated.

The mineral material was left behind

Some crystals form by Precipitating out of Solution

Minerals (solute) dissolve in water (solvent) to create saturated solutions.

Heating the water adds energy to the system, and therefore, more solute can dissolve.

Precipitation of crystals occurs when heated solutions cool.

Minerals dissolved in heated water will precipitate out from the solution and form crystals.

Ex. This phenomenon occurs at hot springs like the ones in Yellowstone National Park. As the thermally heated water from the underground hot springs reaches the surface and cools, minerals dissolved in the hot water precipitate from the solution.

These salt crystals formed from salt water because as the water

evaporated, the salt wasn’t dissolved anymore. So the

chemical energy in salt takes over and crystals form.

3,000 minerals exist on Earth

Only around 20 are considered commonThese minerals form rocks

10 of these make up 90% of Earth’s crust.Quartz, orthoclase, Plagioclase, Muscovite, Biotite, Calcite, Dolomite, Halite, Gypsum, and Olivine/Pyroxene/Amphiboles.

Basic Properties Used to Identify:ColorCleavageHardnessStreakLusterDensityCrystal Shape

Some minerals display strange properties. These can include: Magnetism, fluorescence, and

reactivity.

These minerals glow in the dark.

A black light really brings it out!

The minerals inthis rock react

with acid

Fizzing!

The particles of mineralsof this rock act like magnets

Rocks are nothing more than a mixture of different mineral crystals.

Quartz + Biotite + Feldspar =

Granite

This is Continental Crust

***All three minerals are combined in a Granite rock

(mineral) (mineral) (mineral) (Rock)

Pyroxene + Olivine = Basalt

This is Oceanic Crust

***Both minerals combined make Basalt

(mineral) (mineral) (rock)

Two Main Groups of MineralsSilicate Minerals 96% of Earth’s crustComposed of silicon (Si) and oxygen (O)Quartz is pure Si and O, others contain other

elements as well.

Non-Silicate Minerals4% of Earth’s crustIncludes: Carbonates, Halides, Native

elements, Oxides, Sulfates, and Sulfides.

Chemical compositionGold, Silver, Sulfur

Native elementsAu, Ag, S

SulfidesPyrite, Galena FeS, PbS

Hematite, Magnetite Fe2O3, Fe3O4

Oxides

Silicates Quartz, Mica, Feldspar

SiO2

KAl2(AlSi3O10)(OH,F,Cl)2

KAlSi3O8

Silic- is for Silicon (s)

Silicates

-ate is a suffix for “oxide “

Silicates are “oxides of silicon”

Quartz Mica

KAl2(AlSi3O10)(OH,F,Cl)2SiO2

Can you find the “silica” ?

Silicates

Silica Structure

4 oxygen atoms for every 1 silicon atom

Olivine

Feldspar, Quartz

Micas

Amphibole (Hornblende)

Pyroxenes (Augite)

Complexity Temp.

Chemical formula:

CChemical formula:

C

Graphite Diamond

How can 2 minerals with the same composition be so different?

What’s the point here?

“Internal Arrangement of Atoms” controls most physical properties!

Review of Concepts:

1. Minerals can be identified by examining….. Physical Properties, including….

Luster, Hardness, Cleavage, Color, Streak, Density….

2. Minerals are classified according to their….. Chemical Composition, including groups like….

Native Elements, Sulfides, Oxides, and the all important SILICATES

3. The “Basic Building Block” of the Silicate Minerals is…..

Review of Concepts: (continued)

4. The physical properties of minerals are generally controlled by…..Crystalline Structure….

…or the “orderly internal arrangement of the atoms”!

What do graphite and diamond have in common?……

Identical Chemical Composition….

What accounts for the differences between graphite and diamond?

….the “orderly internal arrangement of the atoms!