Mineral Identification Mr. Jensen Ref: McGuire – ES/PS.

Mineral IdentificationMineral Identification

Mr. Jensen Mr. Jensen Ref: McGuire – ES/PSRef: McGuire – ES/PS

Identifying MineralsIdentifying Minerals

• Minerals can be identified using their distinctive physical and chemical properties.

• Mineral properties include:– Color – Luster– Hardness– Cleavage– Streak– Characteristics– Composition

Table 2-1: Table 2-1: Common Common

Rock Rock Forming Forming MineralsMinerals

Minerals: ColorMinerals: Color

• Color– Many minerals have a

characteristic color– Impurities may discolor

certain light colored minerals

• Ex. Quartz and calcite which are typically colorless.

– Dark color minerals typically do not have this problem.

Minerals: LusterMinerals: Luster

• Luster– Describes the way light is reflected from the

freshly cut surface of a mineral.– Metallic Luster

• Hard shiny look like polished metal.• Light is unable to penetrate.• Ex. Pyrite, galena and magnetite

– Non-Metallic Luster• May be shiny but some light is able to penetrate.• Includes glassy, waxy, pearly and earthy (dull) lusters• Ex. Calcite, quartz and feldspar

Minerals: StreakMinerals: Streak

• Streak– The color of the mineral in

a powder form.– The test for streak is

performed by rubbing a fresh corner of the mineral across a white, unglazed streak plate.

– Several minerals have a streak that is not the same color as the mineral itself.

• Most metallic luster minerals have a dark colored streak. (Ex. Graphite, Pyrite)

Minerals: Crystal StructureMinerals: Crystal Structure

• Crystal Structure– Minerals form

characteristically shaped crystals

– A crystal is a regularly shaped solid formed by an ordered pattern of atoms.

Minerals: HardnessMinerals: Hardness• Hardness

– Minerals differ in hardness

– Tested by scratching mineral with other materials of known hardness

– Friedrich Mohs (Geologist) created the Moh’s scale for hardness

Minerals: CleavageMinerals: Cleavage

• Cleavage– If a mineral breaks readily

along flat surfaces it shows cleavagecleavage

– Many minerals break along flat surfaces called cleavage planescleavage planes

– Minerals that break along even surfaces that do not follow atomic arrangement (crystal faces) are said to show fracturefracture

Minerals: DensityMinerals: Density

• Density– Minerals vary in density and specific gravity

(ratio of density and water)