Physical properties of soil

Physical properties of soil

1.    Color

2.    Streak

3.    Hardness

4.    Luster

5.    Crystal form

6.    Cleavage

7.    Taste

8.    Specific gravity

9.    Magnetism

10.           Effervescence

11.           Fluorescence

Color:-

Ø Denotes the natural color of the mineral

Ø The most obvious, but least reliable

Ø Calcite has more colors

Ø Sulfur and pyrite have same color

Streak:-

Ø Refers to the color of the powder form of the mineral when an unknown mineral is rubbed against a piece of unglazed porcelain (streak plate) it produces a colored line.

Ø Hematite       -        red

Ø Magnetite     -        black

Ø Talc                -        white

Fracture and cleavage:- these terms describe the way a mineral breaks fracture is the nature of the surface produced as a result of its breakage.

Conchoidal         -        curved surface

Uneven              -        uneven surface

Hackly                -        jagged surface

Earthy                 -        like chalk

Even                   -        smooth

Cleavage:- some minerals break along certain well defined planes called cleavage planes.

Gypsum    -        1 set

Calcite       -        2 sets

Fluorite     -        3 sets

Hardness:- this is how resistant a mineral is to being scratched, we use the Mohs scale to classify a given minerals hardness. Try to scratch the unknown mineral with various items, such as a fingernail (hardness of about 2.5), a coin (3), a steel nail (5.5)

Luster:-  the way a mineral reflects light metallic (magnetite); sub-metallic, vitreous(opal), resinous(pyrite), silky(asbestos) and greasy

Crystal from:- crystal form is the result of regular grouping of atoms that are homogeneous. A crystal is a polyhedral form, which means it is a geometric solid. It has a specific set of facts, corners and edges, which is consistent with the geometric packing of the atoms.

These are six basic crystal forms:

1.    Isometric

2.    Tetragonal

3.    Hexagonal

4.    Orthorhombic

5.    Monoclinic

6.    Triclinic

Taste:- this property is used to identify the mineral halite (salt)

Specific gravity:- this characteristics relates to the minerals density. If the minerals is heavy for its size, then it has a high specific gravity.

Magnetism:- is the mineral magnetic(try using a compass) or is it attracted by a magnate? This property is characteristic of magnetite.

Effervescence:- when some mineral are expected to acids, they begin to fizz(calcite)

Fluorescence:- some minerals display the phenomenon of photoluminescence. They glow when exposed to U.V rays.