THE CASE OF THE SCARLETT STREAK MINERAL IDENTIFICATION

THE CASE OF THE SCARLETT STREAK: MINERAL IDENTIFICATION Virginia T. Mc. Lemore New Mexico Bureau of Geology and Mineral Resources New Mexico Tech

What is a mineral?

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?

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 2002 -2005 (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 Hardness

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 Cleavage • determine the angular relation between the resulting cleavage surfaces – perpendicular – acute – obtuse

www. ironorchid. com/minerals/

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

Streak

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 - Yellowbrown • Hematite - Redbrown

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

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

Luster

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

www. ironorchid. com/minerals/

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/minerals. htm

• Crystal shape • six crystal systems • governed by the mineral's internal structure Habit • • • 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. . .

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