Presentation on theme: "THE CASE OF THE SCARLETT STREAK: MINERAL IDENTIFICATION Virginia T. McLemore New Mexico Bureau of Geology and Mineral Resources New Mexico Tech."— Presentation transcript:
THE CASE OF THE SCARLETT STREAK: MINERAL IDENTIFICATION Virginia T. McLemore New Mexico Bureau of Geology and Mineral Resources New Mexico Tech
What is a mineral?
naturally occurring inorganic solid homogeneous crystalline material with a unique chemical element or compound with a set chemical formula usually obtained from the ground
A crystal is composed of a structural unit that is repeated in three dimensions. This is the basic structural unit of a crystal of sodium chloride, the mineral halite.
Why are minerals important?
Identification of rocks commodities that we use every day foundation of understanding geology and geologic processes that affect us everyday understanding geologic hazards
Minerals have distinctive physical and chemical properties that allow for their identification.
Properties of minerals Habit (Crystal forms and shapes) Hardness Cleavage Streak Color Luster Transparency Twinning Fracture Specific Gravity Associated Minerals Fluorescence Magnetism Odor Feel Taste Solubility Reaction to acids Radioactive minerals Meteoritic minerals
ease or difficulty with which the mineral can be scratched controlled by the strength of bonds between atoms
Way the mineral breaks or fractures one direction of weakness, or in other minerals, 2, 3, 4, or as many as 6 may be present determine the angular relation between the resulting cleavage surfaces –perpendicular –acute –obtuse
color of a mineral when it is powdered crushing and powdering a mineral eliminates some of the effects of impurities and structural flaws Black - Graphite Black - Pyrite Black - Magnetite Black - Chalcopyrite Gray - Galena Limonite - Yellow- brown Hematite - Red- brown