Characteristics of Minerals: A. naturally occurring B. solid C. inorganic D. definite crystal structure E. definite chemical composition

Inorganic- does not come from materials that were once living. ***Coal is not a mineral because it comes from remains of plants & animals. It is organic.

Properties of Minerals: A. Hardness (Moh’s hardness scale; 1 softest, 10 hardest)

B. color C. streak- color of mineral’s powder when rubbed against a streak plate D. luster- how light is reflected from its surface (shiny, metallic, dull, waxy, glassy)

E. Density (mass/volume) F. crystal shape (cubic, hexagonal) G. cleavage- splints easily along flat surfaces H. fracture- how it looks when broken (jagged, curved, crumbled)

I.reacts with dilute Hydrochloric acid to produce carbon dioxide gas bubbles J. special properties: magnetic, fluorescent, radioactive

Mineral Formation 1. Cooling of magma or lava As magma cools, the elements in magma may combine chemically to form minerals. Cooling rate determines crystal size. Slow cooling creates large crystals such as quartz. Fast cooling creates small crystals. If molten material runs into water, it may cool so quickly that no crystals form.

Sometimes flowing magma or lava fill cracks of surrounding rock. The rock traps the heat from the molten material causing it to cool very slowly and to form large mineral crystals. Veins of some gems and rare minerals form in this way. Ex: diamonds, emeralds & rubies

2. Minerals from liquid solution When liquids evaporate, the elements stay behind and may form minerals. Ex: salt crystals which form the mineral halite. When a solution becomes saturated, dissolved material may crystallize out of solution. Water carrying minerals sometimes seep into cracks of rock. Slow evaporation in the cracks can also form mineral veins.

3. Minerals from hot water solutions Sometimes the elements that form a mineral dissolve in hot water. Molten material heats this water to high temperatures beneath earth’s surface. When the solution cools, elements & compounds crystallize out as minerals. Pure metals such as silver & gold are formed in veins from this process.

These two mineral samples look very similar, but one is quartz and one is calcite. Describe the process that you would follow to identify which is which.