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.