Rocks, Minerals, & Elements
 Rocks  Minerals  Atoms

Rocks, Minerals, & Elements
 Rocks = a collection of one or more minerals
 Minerals = a collection of one or more elements (atoms) rocks minerals atoms granite quartz + feldspar + biotite quartz = silicon + oxygen

Atomic Building Blocks
 There are 117 known elements (as of 2006), but only 92 occur naturally

Atomic Building Blocks
 The two most common elements in the Earth’s crust is oxygen and silicon.
 8 elements make up the vast majority of the crust’s composition
Earth’s
Crust

Tarbuck & Lutgens

What is a Mineral?
 Minerals are the combination of one or more elements
• Solid
• Occurs naturally
• Inorganic
• Definite crystalline structure
• Definite chemical composition
SOIDD – stupidity occurs in daily doses
Celestian

Making Minerals
 Minerals can crystallize from
COOLING MAGMA
 Minerals can crystallize from a solution (body of water) due to
 Evaporation
OR
 Precipitation


Over 4000 known minerals

8 main mineral groups

Classified by most significant ions
MAGNESITE
Celestian

4
• >90% of all minerals on Earth’s crust
• Composed of the silica tetrahedron
• Insoluble
• Common minerals: quartz, feldspar, mica
• Use: bricks, glass, insulation, jewelry, electronics

3
• Common mineral: calcite (forms the rock limestone)
• Soluble in wet climates (cave former)
• Use: cement, filler and whitener in plastic pipe, paper, and toothpaste

4
• Common mineral: gypsum
• Soluble
• Uses: drywall, soil conditioner, hard cast for broken bones

4
• Common mineral: apatite
• Use: fertilizer

• Common minerals: Hematite, magnetite, chromite
• Metals combine with oxygen
• Uses: ores of iron, titanium tin, manganese, etc.
Hematite

• Common minerals: Sphalerite, Cinnabar,
Chalcopyrite, Galena, Pyrite
• Unstable at Earth’s surface – alter to sulfate ions
Pyrite
• Cause water pollution
• Uses: ores for zinc, mercury, copper, lead, iron

• Common minerals: Halite, fluorite
• Extremely soluble
• Uses: salt, steel making, fertilizer
Halite

• Common minerals: Gold, silver, platinum, copper, sulfur, diamond, graphite
• Composed of a single atom type
• Use: jewelry, electrical parts, lubricants, etc.
Graphite Gold in quartz

Physical Properties of Minerals
Luster
 How a mineral reflects light (metallic OR nonmetallic)

Physical Properties of Minerals
 Resistance to scratching
Hardness

Physical Properties of Minerals
Cleavage
 Planes of weakness in a mineral mica calcite

Physical Properties of Minerals
Color
 Largely dependant on composition
Quartz
Smokey quartz
Amethyst (purple quartz)

Physical Properties of Minerals
Streak
 The color of a mineral when powdered
Hematite displaying a reddish streak

Physical Properties of Minerals
Specific Gravity
 Density of a mineral relative to water (1.0 g/cm 3 ) higher (10-20 g/cm 3 ) lower (2-3 g/cm 3 )

Physical Properties of Minerals
Crystal Form
 Unique forms controlled by a mineral’s atomic structure

Physical Properties of Minerals
Others
 magnetism
 effervescence
 fluorescence
 Crystal striations