SIR C R REDDY (A) COLLEGE N.GANESH 5133 III-B.Sc (2016-17)

Physical properties of minerals A mineral should be definite solid substance having chemical composition The physical structure of mineral is formed by the crystal

Physical properties are observed eye in proper light A mineral should be studied by physical, chemical and optical properties Physical properties are observed eye in proper light

Different physical properties Depending on light Colour Form Streak Lustre Cleavage Fracture Hardness Specific gravity Depending on light Senses Inner atomic structure Specific gravity of minerals Properties depending on heat Magnetism radioactivity

Colour Depends on obsorption and reflection A mineral occurs in different colours Ex : quartz Ex : calcite

Form Crystal structure Depends on the group of crystal structure Crystal character of the minerals is called crystal structure Important forms are Bladed form Tabular form Acicular form Fibrous Platy Columnar Reni Granular Prismatic grains Crystal structure

Acicular form and prismatic grains

Streak It is the colour of the mineral powder Streak tested on the streak plate It is mode of unglazed porcelane Streak and colour of minerals may be same or different

Lustre It is amount of reflection of light on the mineral surface. They are different types Intensity of lustre is called splended Metallic Adamantine Vitreous Resinous Greasy Waxy Pearly Silky...........etc

Cleavage

Fracture It is broken surface of the mineral Different types Conchoidal Even Uneven Hackly fracture

Concoidal fracture It is the curved concave surface It shows concentric lines If it is less clear than the subconcoidal Ex : Quartz concoidal fracture -----

Even fracture Even fracture : The mineral surface will be even Ex : chert Even fracture :

Uneven Surface will be ruff and irregular Ex : Limestone------- Uneven Fracture-------

Hackly fracture The surface will have projection of crystals Ex : Asbectas , Zeolites Hackly Fracture==

Hardness It is resistance offered by mineral to the pressure applied

Specific gravity It is the amount of substance , the ratio of the weight equal to the volume of water Amount of water displaced by a substance is it’s specific gravity Picnometer is used to measure the specific gravity Chemical balance , spring , walkers , steel yard method ......................etc.

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