Minerals What is a mineral Naturally occurring Inorganic

Minerals

What is a mineral? • Naturally occurring • Inorganic (non-living) • Characteristic chemical composition • Solid • Crystalline structure- specific arrangement of atoms

How is matter classified? • Element • Cant be separated into simpler substances • Atom – smallest part of an element that has all of its properties. • Molecule – 2 or more atoms chemically combined. • Compound – 2 or more elements chemically combined. • Mixture – 2 or more substances physically combined.

Grouped by Chemical Composition • Silicates – Compound of silicon and Oxygen, make up 75% of all minerals. Quartz is the most common silicate. • Carbonates – Compound of carbon and Oxygen. Calcite is the most common carbonate.

Crystal Size Large Size crystal are formed during a slow cooling rate. Small size crystals are formed during a fast cooling rate. If the cooling is very fast no crystals may form. An example are minerals formed from lava.

Mineral properties • Color • Luster • Habit (Shape) • Cleavage & Fracture • Streak • Hardness • Other – magnetic, florescent, smell

Color: Easily observed, least reliable to ID mineral.

Luster: How minerals reflect light from its surface. Metallic Nonmetallic

Crystalline structure Characteristics shape of mineral resulting from atoms and molecules coming together when mineral forms

Cleavage & Fracture Cleavage: Mineral breaks along smooth definite surfaces. Fracture: Mineral breaks along rough or jagged surfaces.

Cleavage & Fracture Best identified on a fracture surface

Streak Color of powder when scraped against a rough surface. Color stays the same for each mineral

Specific Gravity • Specific gravity – Measure of density of mineral in air compared to density of mineral in water.

Hardness Ability of a mineral to resist being scratched. Hardness tests uses the Mohs Scale of Hardness. 2. 5 Fingernail 3. 5 Penny 4. 5 Iron nail 5. 5 Glass 6. 5 Streak plate