Minerals

Humans cannot survive without minerals

• 16 minerals needed for humans to survive

• .03% of what we eat but we would not survive without the minerals

• Sodium, potassium, calcium, magnesium, copper, phosphorous

Minerals make-up many practical parts of our lives

Glass is made from 6 minerals

• Silica• Limestone• Magnesium • Boric acid• Soda• Aluminum• 40 billion glass

containers/year in USA• 35 % are recycled

Gold in California

• Discovered in the American River, 1848

• Gold Rush- 1849• Population of SF- 575

males,177 females, 60 children- March, 1848

• 100,000- December 1849• Chinese, Welsh, German,

English, Mexican, Spanish and French

• Diversity of California

Salt

• Early people collected salt before they understood how important the mineral is for survival

• Mediterranean-salt cakes were used as money

• Greeks traded salt for slaves

• England flourished when fuel for boiling brine changed from wood to coal

Minerals are mined for our use

Magmatic copper, magnetite, uranium

What is a mineral?

• Naturally occurring• Inorganic• Crystalline structure

Halite, salt, sodium chloride

Atoms make-up minerals

• An atom is the smallest component of matter

• Each element is defined by the number of protons

• The atom must be electrically neutral

• The number of protons equals the number of electrons

http://www.howstuffworks.com/atom/htm#

Eight elements make-up 99% of the Earth’s crust

Silicon and oxygen make-up 70 % of the Earth’s crust

Why do atoms combine to form minerals?

• Write the following questions and answer in your notes:

• Look at the salt with the hand lens

• What is the color?

• What is the shape of the crystals?

• Does the shape match the halite crystals?

• What is a distinguishing characteristic of salt?

Salt is also named Sodium Chloride

• Look at the periodic table:• Write the chemical notation, atomic

number and atomic weight for sodium and chlorine

• Now sketch an atom with the nucleus containing the correct number of protons and neutrons

• Sketch the electrons on the “rings” around the nucleus

Sodium chloride: sketch a diagram of the sodium and

chlorine atoms

Why do sodium and chlorine combine to form salt?

• Explain why sodium and chlorine combine to form salt

The configuration of electrons determines if an atom will respond

with another atom

The sodium atom has one electron on its outer ring. The Chlorine atom has 7 electrons on its outer ring. The two atoms share electrons forming an ionic bond.

Atomic structure determines the mineral’s characteristics

Salt or halite always has a cubic form and tastes salty.

Cations and Anions

• The one electron on the outer shell is given up

• This leaves the sodium atom with more protons, +1

• The one electron is added to Chlorines outer shell

• This leaves the chlorine atom with one more electron, -1

cation anion

Mineral Formation

• Cooling of magma: crystallization

• Evaporation: salt• Hydrothermal

Silicate minerals are the building block of igneous rocks

Mountains, British Columbia

Granite: individual minerals make-up the rock

Minerals are the building block of rocks

Feldspar crystal

Biotitie

Quartz

Hornblende

Minerals can be identified by physical properties

• Crystal habit

• Cleavage

• Fracture

Quartz has a conchoidal fracture Mica has a single, perfect cleavage

Equant garnet: same dimension in all directions

Color

malachite

sulfur

apatite

Hardness

How the mineral can be scratched

• Fingernail• Penny• File or knife

Streak

• Minerals leave a distinct residue on a porcelain plate

Luster

• Metallic or non-metallic

Classification of Minerals

• Composition

• Rock forming minerals contain silicon and oxygen

The silicon tetrahedron

The arrangement of the silicon tetrahedron determines the mineral’s

shape

Biotite: sheet structure; breaks easily on one surface

Olivine

Hornblende: double chain

Mineral Classification: based on dominant element

Pyrite: fool’s gold; FeS2

Sulfides: contains the element sulfur

Galena: PbS; important ore of lead

• Carbonates: contains calcium carbonate; CaCO3

Mineral Classification: based on dominant element

Calcite: CaCo3Dolomite: CaMg(CO3)2

Summary

• Mineral definition• How do minerals form?• Read and understand information associated

with the periodic table of the elements• Be able to sketch a diagram of an atom:

hydrogen, helium, carbon, sodium, chlorine• How are minerals classified: rock forming

minerals? Silicates, sulfides, carbonates• Name and describe the physical characteristics

to distinguish minerals.