minerals and its properties

minerals

•       Substance which having the following five criteria is known as mineral.

1. Solid
2. Naturally occurring
3. Inorganic
4. Fixed chemical formula
5. Specified atomic structure

Occurrence of materials

•       Minerals occur as crystals i.e. bodies of geometric shapes which are bounded by faces arranged in a regular manner and related to internal atomic structure.

•       Crystal Faces: smooth planar surfaces of definite geometrical shapes.

CRYSTAL SYSTEMS

cube crystal

In total we have six crystal systems

1. Cubic
2. Hexagonal OR Trigonal
3. Tetragonal
4. Orthorhombic
5. Monoclinic

6.               6, Triclinic

Crystal system

Plane of symmetry

•       Plane of symmetry is a plane in which crystal is divided into equal halves and both are the mirror image of each other.

PHYSICAL PROPERTIES OF MINERALS

•       This includes color, luster, hardness, cleavage, fracture, tenacity, habit, streak, diaphaneity, magnetic property, specific gravity.

•       Except this some minerals have their own property which is named as special property. For example, sulphur having property of odor or a pungent smell, magnetite having special property of magnetism, etc.

•       COLOR:
some minerals have distinctive color like sulphur have yellow color.sometimes traces of other minerals changes the appearance color of specific minerals. So it  is identify a pure mineral we have to conduct streak test. Streak gives the powder of mineral which is mostly pure and shows the true color of mineral.

•       Luster: 
It is the appearance of mineral surface in reflected light it may be metallic or dull.

•       Hardness:
It is basically strength or resistance against abrasion. For finding out the hardness

 we have two methods one is direct method and other one is indirect method.

Hardness scales

•       Finger nail - 2.5

•       Copper coin – 3.5                                             

•       Iron nail- 4.5

•       Sharp glass- 5.5

•       Streak plate – 6.5

   •       CLEAVAGE:   Some minerals have tendency to split along some regular planes. These smooth plane surfaces are known as cleavage planes.

                                                             

•       Fracture:   the nature of broken surface of mineral is known as fracture. The break become irregular and independent of cleavage.

                The fracture may be conchoidal (curved), Even (nearly flat), uneven (rough) and hackly (small sharp irregularities)

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•      TENACITY:   The response of mineral of hammer blow, to cutting with a knife and to bending is described by its tenacity. The minerals whose shape can change under the above said actions are known as MALLEABLE, otherwise most minerals are brittle.

HABIT:   Natural shape of mineral. It may be crystalline, cryptocrystalline and amorphous

•       DIAPHANEITY:   The ability of passing light or the transparency of the mineral is technically known as Diaphaneity. MINERAL may be transparent, translucent or opaque.

SPECIAL PROPERTIES

•       MAGNETISM: attracted to a magnet contains iron, nickel, cobalt or magnetite.

•       DOUBLE REFRACTION: Can see doubling of things but it is so weak in most of the minerals.

E.g Iceland spar variety of calcite

•       FLOURESCENCE:  glows under ultraviolet light.

e.g: autunite mineral

•       Phosphorescence: continues to glow after the removal of UV light. E.g: Celestine

•       Piezoelectric Electricity : generated from some mechanical stress or pressure.  E.g quartz, topaz etc.

structure geology

The study of deformation of rock within the earth's geosphere is called structure geology. (deals with the study of the forces that bring about the deformation).

Faults

Faults doesnot always bend sometime its break. When rocks move and breaks is called faults

Types of faults

•       Reverse fault

•       Normal fault

•       Thrust fault

•       Strike slip fault