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

NEW MEXICO MINING: WHERE ARE THE DEPOSITS?

New Mexico is at the edge of one of the world’s greatest metal-bearing provinces

Active mines in New Mexico (excluding aggregates)

Active aggregate mines in New Mexico.

Stone House zeolite mine, Sierra County (18.3 million tons of reserves).

Metals districts with Significant deposits in New Mexico

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

Hardness

ease or difficulty with which the mineral can be scratched controlled by the strength of bonds between atoms

Cleavage

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

From:geology.csupomona.edu/alert/mineral/minerals.htm

Streak

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

From:geology.csupomona.edu/alert/mineral/minerals.htm

academic.brooklyn.cuny.edu/geology/leveson/core/linksa/mineral_id...

Luster

way a mineral’s surface reflects light metallic earthy waxy greasy vitreous (glassy) adamantine (or brilliant, as in a faceted diamond) From:geology.csupomona.edu/alert/mineral/minerals.htm

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

Color From:geology.csupomona.edu/alert/mineral/minerals.htm

Habit Crystal shape six crystal systems governed by the mineral's internal structure triclinic monoclinic orthorhombic tetragonal hexagonal isometric From:geology.csupomona.edu/alert/mineral/ minerals.htm

Specific Gravity specific gravity –ratio of mineral density to the density of water similar to weight density –ratio of the mass of a mineral to its volume

academic.brooklyn.cuny.edu/geology/lev eson/core/linksa/mineral_id...