Dr. Dimpal Zambare 1st Year P.G. R & B Dept.
Colour Nature Lustre Asterism Streak Diapheneity Cleavage Fracture Elasticity Hardness Spefic gravity
Taste Odour Porosity Feel
Colour is usually the first property of minerals which is noted. A mineral gives a constant distinctive colour, when observed on freshly broken surface. Though this property is not clear in many minerals,commercial minerals by and large are distinguished by their typical colour.
Being natural chemical compounds,minerals may occur in any aggregation state,though most of them are known to belong to solid crystalline substances. As such,natural occurance of minerals may be in the following forms1. crystalline 2. amorphus 3. opaque,transparent,translucent 4. aggregate
It may be defined as appearance of a surface in reflected light. Two general types of lustre 1. Metallic 2.Non metallic Subtypes of non-metallic lustre are as follows: 1. Adamantine 2. Vitreous 3. Resinous 4. Pearly 5. Silky
Some minerals exhibit concentration of light along lines radiating from a center,a property called asterism in reference to its star like appearance. This concentration results from twinning or from regularly oriented inclusions.
Some saphires & rubies have this property when viewed in reflected light
The colour which is produced by rubbing a mineral on unglazed porcelain is known as streak of that mineral.
The colour of streak may or may not be same as colour of mineral Some minerals, mainly those whose hardness is greater than that of unglazed porcelain, are usually considered to have no streak at all.
It is stated in terms of relative ability of minerals to allow light to pass through them 3 stages are generally recognized: 1. Opaque – e.g. graphite 2.Transparent-e.g. colourless quartz 3.Translucent-e.g.chalcedony
It is property of mineral to split along definite planes This property is constant with regard to no. of planes & direction in all specimens of any given mineral, although it may vary in regard to quality. Cleavage may be described in order of quality as: 1. perfect or eminent 2. good or distinct 3. poor or indistinct
It includes all surfaces of breakage other than planes of cleavage or parting. Types of fracture: 1. Conchoidal 2. Hackly 3. Uneven 4. Even 5. Earthy
The elastic qualities of minerals are so varied that considerable no.of types or degrees are recognized. Types : 1. Elastic 2. flexible 3. Malleable 4. Ductile 5. Sectile 6. Brittle
Hardness of the mineral is its resistance to scratching. It is relative parameter. In mineralogy relative hardness is always determined by using set of minerals known as Moh’s scale of hardness. 1 Talc 6 Orthoclase 2 Gypsum 7 Quartz 3 Calcite 8 Topaz 4 Fluorite 9 Corundum 5 Apatite 10 Diamond
Specific gravity of any substance is ratio of its weight in air to the weight of an equal volume of water. The specific gravity of natural mineral is known to vary from 0.8 to 21.
One of the minor properties of minerals is taste of some which are soluble in water. Types of tastes are as : Acid or sour Alkaline-such as taste of soda Astringent-such as taste of alum Saline etc. This property is restricted to relatively small no. of minerals & is not especially diagnostic
Although most minerals have no inherant odour a few do have characteristic smell when struck with a hammer,crushed,heated or breathed upon. Types of odour: Sulfurous-odour of burning sulfur Alliaceous-odour of arsenic or garlic Foetid - odour of rotten eggs etc.
Some minerals absorb water so readily that they will adhere to the tongue. This property is restricted value in mineral determinations but is useful in special instances
Certain minerals have distinctive feel which may be of some value in determing them.
e.g. Minerals which conduct heat very well tend to have a cold feel, talc & graphite have greasy feel, chalk is characterised by harsh or meager feel
अभ्रवैक्रान्तमाक्षीकववमलाविजसस्यकम् । चपलो रसकश्चेवि ज्ञात्वाष्टौ संग्रहे िसान् ॥ र.र.समु .2/1
Nature
platy
Colour
Greenish black
Streak
Greenish black
Cleavage
Perfect
Fracture
Uneven
Lustre
Splendent
Tenacity
Flexible
Transparency
Translucent
Hardness
2.5to3
Sp. gravity
2.6to3
Nature
Crystalline prismatic
Colour
Black
Streak
Colourless
Cleavage
None
Fracture
Uneven
Lustre
Vitreous
Tenacity
Brittle and often rather friable
Transparency
Translucent
Hardness
7 to 7.5
Sp. gravity
3 to 3.5
Crystallisation
Tetragonal
Colour
Brass yellow
Streak
Greenish black
Cleavage
Indistinct
Fracture
Uneven
Lustre
Metallic
Tenacity
Brittle
Transparency
Opaque
Hardness
3.5 to 4
Sp. gravity
4.1 to 4.4
crystallisation
Isometric, diploidal
Colour
Pale,brass yellow
Streak
Greenish or brownish black
Cleavage
Very poor or lacking
Fracture
Conchoidal to uneven
Lustre
Metallic
Tenacity
Brittle
Transparency
Opaque
Hardness
6 to 6.5
Sp. gravity
5.01
Nature
-
Colour
Black
Streak
-
Cleavage
-
Fracture
-
Lustre
Greasy /resinous
Tenacity
-
Transparency
Opaque
Hardness
2
Sp. gravity
1.2
Nature
Crystalline lumps
Colour
Bright & deep blue
Streak
Pale blue to colourless
Cleavage
Poor
Fracture
Conchoidal
Lustre
Metallic
Tenacity
Brittle
Transparency
Translucent
Hardness
2 to 2.5
Sp. gravity
2.12 to 2.3
Nature
Crystalline
Colour
Lead-grey
Streak
-
Cleavage
-
Fracture
Sub-conchoidal
Lustre
Metallic
Elasticity
Flexible & sectile
Hardness
2
Sp. gravity
6.4 to 6.8
Nature
Crystalline
Colour
Orange yellow to deep red
Streak
Orange yellow
Cleavage
basal,perfect
Fracture
Conchoidal
Lustre
Sub-adamantine
Tenacity
Brittle
Transparency
Transparent in very thin pieces
Hardness
4
Sp. gravity
5.6
गन्धाश्मगैररकासीसकां क्षीिालविलाञ्जनम् । कङ्कुष्ठ चेवि उपरसश्चाष्टौ पारदकमम वि ॥ र.र.समु .3/1
Nature
Crystalline lumps
Colour
Yellow,yellowish brown
Streak
Yellowish white
Cleavage
Poor
Fracture
Conchoidal
Lustre
Resinous
Tenacity
Brittle
Transparency
Translucent
Hardness
1.5 to 2.5
Sp. gravity
1.95 to 2.10
Nature
Massive clayey
Colour
Reddish brown
Streak
Reddish brown
Cleavage
-
Fracture
Uneven
Lustre
Earthy
Tenacity
Brittle
Transparency
Opaque
Hardness
5.5 to 6.5
Sp. gravity
2.7
Nature
Massive lumps
Colour
Greenish white
Streak
White
Cleavage
None
Fracture
Uneven
Lustre
Earthy
Tenacity
Brittle
Transparency
Translucent
Hardness
1.95 to 2
Sp. gravity
1.90 to 1.97
crystallisation
Hexagonal, ditriogonal
Colour
White
Streak
White
Cleavage
Basal,distinct to indistinct
Fracture
Splintery to conchoidal
Lustre
Vitreous to dull
Tenacity
Brittle
Transparency
Transparent to translucent
Hardness
3.5 to 4
Sp. gravity
2.6 to 2.9
Crystallisation
Monoclinic ,prismatic
Colour
Lemon yellow to brownish yellow
Streak
Pale yellow
Cleavage
Distinct
Fracture
Uneven
Lustre
Pearly to resinous
Tenacity
Imperfectly sectile
Transparency
Translucent to opaque
Hardness
1.5 to 2
Sp. gravity
3.5
Crystallisation
Monoclinic, prismatic
Colour
Red to orange yellow
Streak
Red to orange yellow
Cleavage
Distinct
Fracture
Conchoidal
Lustre
Resinous to greasy
Tenacity
Sectile
Transparency
Transparent to translucent
Hardness
1.5 to 2
Sp. gravity
3.5
Crystallisation
Orthorhombic,di-pyramidal
Colour
Lead grey to steel grey
Streak
Lead grey to steel grey
Cleavage
Perfect
Fracture
Sub-conchoidal
Lustre
Matallic
Tenacity
Highly flexible & slightly sectile
Transparency
Opaque
Hardness
2
Sp. gravity
4.6
Crystallisation
Isometric
Colour
Lead grey
Streak
Lead grey
Cleavage
Perfect
Fracture
Sub-conchoidal
Lustre
Matallic
Tenacity
Brittle
Transparency
Opaque
Hardness
2.5
Sp. gravity
7.6
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