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Mineral Identification. Mr. Jensen Ref: McGuire – ES/PS. Minerals can be identified using their distinctive physical and chemical properties. . Mineral properties include: Color Luster Hardness Cleavage Streak Characteristics Composition. Identifying Minerals. - PowerPoint PPT Presentation
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Mineral IdentificationMr. Jensen
Ref: McGuire – ES/PS
Identifying 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: Common
Rock Forming Minerals
Minerals: 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: 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: 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 Structure
• Crystal Structure– Minerals form
characteristically shaped crystals
– A crystal is a regularly shaped solid formed by an ordered pattern of atoms.
Minerals: 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: Cleavage• Cleavage
– If a mineral breaks readily along flat surfaces it shows cleavage
– Many minerals break along flat surfaces called cleavage planes
– Minerals that break along even surfaces that do not follow atomic arrangement (crystal faces) are said to show fracture
Minerals: Density• Density
– Minerals vary in density and specific gravity (ratio of density and water)