Minerals

Minerals: naturally occurring, inorganic, solid, posses an orderly internal structure of atoms, and have a definite chemical composition. 

I. Is a snowflake of a mineral?

Is it naturally occurring? Yes.

Is it inorganic? Yes.

Is it a solid? Yes.

Does it posses an orderly internal structure of atoms? Yes.

Does it have a definite chemical composition? Yes.

Is a snowflake a mineral? YES!

II. Is a pearl a mineral?

Is it naturally occurring? Yes.

Is it inorganic? No. 

Is a pearl a mineral? No. 

III. Other minerals:

  


IV. Physical properties of Minerals

Minerals have a crystal form: external expression of the internal arrangement of atoms. (Slow cooling = good form; rapid cooling = poor form)

Luster: appearance of a mineral in reflected light. (Metallic and Nonmetallic- silky, dull, earthy)

Color: least reliable property. Highly variable within minerals due to slight chemical changes.

Streak: color of a mineral in its powdered form; helpful in distinguishing different forms of the same mineral.

Hardness: resistance of a mineral to abrasion or scratching; all minerals are compared to a standard scale; Mohs scale of hardness.

Cleavage: tendency to break along planes of weak bonding; produces flat, shiny surfaces; described by resulting geometric shapes (number of planes, angles between adjacent planes).