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  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)

Crystal structure pictures

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