PROPERTIES OF MINERALS

To identify minerals, mineralogists observe the following properties

A.COLOR

mineral's color may change depending on the surface.

B.STREAK

-Color of mineral in powdered form.

-More reliable than color for identification

-Rub the mineral against an unglazed tile called a streak plate

C.HARDNESS

minerals resistance to scratching

CLEAVAGE

• Mineral's resistance to being broken and fracture

• If a mineral breaks or splits apart with smooth surfaces in certain directions

CRYSTALLINE STRUCTURE OR HABIT

• Crystal habit is the ideal shape of crystal faces

• Ideal faces require ideal growth conditions.

• Many descriptive terms are used to characterize habit.

F.DIAPHANEITY/ AMOUNT OF TRANSPARENCY

• ability to allow light to pass through it. This is affected by chemical makeup of the mineral sample.

• Transparency

Transparent: when you can see clearly through it

Translucent: light comes through it but you cannot see clearly through it

Opaque: no light comes through

G.LUSTER

• how light is reflected off a surface

H.TENACITY

describes the minerals' reaction to stress.

BRITTLENESS

a mineral turns into powder

MALLEABILITY

a mineral can be flattened by pounding with a hammer

DUCTILITY

A mineral can be stretched into wire.

FLEXIBLE BUT INELASTIC

Minerals are bent but they remain in the new position.

FLEXIBLE AND ELASTIC

Minerals are bent, and they bring back to their original position.

|.SECTILITY

• Ability of minerals to be sliced by a knife.

THE MOHS SCALE (PRONOUNCED MOZE) WAS INTRODUCED IN 1822. IT ORIGINATED WHEN FRIEDRICH MOHS CHOSE TEN MINERALS AND ASSIGNED NUMBERS TO THEM BASED ON THE RELATIVE EASE OR DIFFICULTY IN WHICH STONE CAN BE SCRATCHED BY ANOTHER.