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Mineral Properties!!. Luster. The luster of a mineral is the term used to describe how light is reflected from a mineral’s surface Metallic Glassy (vitreous) Waxy, greasy, pearly Dull (submetallic) Silky Earthy. Metallic. Glassy. Waxy. Dull (submetallic). Silky. Earthy. Density.
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Luster • The luster of a mineral is the term used to describe how light is reflected from a mineral’s surface • Metallic • Glassy (vitreous) • Waxy, greasy, pearly • Dull (submetallic) • Silky • Earthy
Density • The density of a given substance is the mass per unit of volume • Dividing a sample’s mass by it’s volume will give the density of the material Density = Mass Volume
Hardness • Hardness is one of the best clues one can use to identify minerals • Mohs Hardness Scale • Ranks 10 minerals from softest to hardest
Scratch Test • A mineral can scratch any mineral softer than itself, but can be scratched by any mineral that is harder. • Apatite can scratch Talc, but is scratched by Corundum • How would you determine the hardness of a mineral not on the Mohs scale?
Crystal Systems • Geologists classify how the crystals grow into six different groups based on shape (the number and angle of the crystal faces)
Cleavage and Fracture • Geologists can determine the identity of a mineral by how it breaks or splits. • When a mineral splits easily it is said to have cleavage • Most minerals do not split apart evenly • When a mineral splits unevenly it is called fracture
Special Properties • Fluorescence – some minerals glow under ultraviolet light • Chemical reaction – some minerals will fizz when in contact with acid • Optical properties – some minerals bend light to cause a double image • Radioactivity – some minerals that contain radium or uranium can be detected by a Geiger counter • Magnetism – some minerals are natural magnets that attract iron