|
Form
|
Tetrahedral, dodecahedral
|
|
Colour
|
White, yellow, brown
|
|
Luster
|
Resinous
|
|
Streak
|
Pale brown to yellow
|
|
Hardness
|
3.5-4.0
|
|
Clevage
|
Perfect
|
|
Fracture
|
Conchoidal
|
|
Sp. Gravity
|
3.9-4.1
|
|
Chemical composition
|
(Zn,fe)s
|
|
Form
|
Tabular, botrydal
|
|
Colour
|
Red, brown
|
|
Luster
|
Metallic
|
|
Steak
|
Reddish brown
|
|
Hardness
|
5.5-6.5
|
|
Clevage
|
None
|
|
Fracture
|
Uneven to subconchoidal
|
|
Sp. Gravity
|
5.2
|
|
Chemical composition
|
Fe2O3
|
|
Form
|
Amorphous
|
|
Colour
|
Yellow brown
|
|
Luster
|
Dull, vitreous
|
|
Streak
|
Yellow to brown
|
|
Hardness
|
4-5.5
|
|
Clevage
|
None
|
|
Fracture
|
Uneven
|
|
Sp. Gravity
|
2.7-4.5
|
|
Chemical composition
|
FeO(OH).nH2O
|
|
Form
|
Prismatic, Crystalline
|
|
Colour
|
Colourless, white, Purple, Pink
|
|
Luster
|
Vitreous, Adamantine
|
|
Steak
|
Colourless
|
|
Hardness
|
7
|
|
Cleavage
|
Indistinct
|
|
Fracture
|
Conchoidal
|
|
Sp. Gravity
|
2.6-2.7
|
|
Chemical Company
|
SiO2
|
|
Form
|
Prismatic, granular
|
|
Colour
|
White, gray
|
|
Luster
|
Vitreous
|
|
Streak
|
White
|
|
Hardness
|
6-6.5
|
|
Cleavage
|
Perfect
|
|
Fracture
|
Uneven
|
|
Sp. Gravity
|
2.5-2.6
|
|
Chemical composition
|
K(AlSi3O8)
|
|
Form
|
Prismatic, Tabular
|
|
Colour
|
Black, Dark green
|
|
Lustre
|
Vitreous
|
|
Streak
|
Colourless
|
|
Hardness
|
5-6
|
|
Cleavage
|
Imperfect
|
|
Fracture
|
Uneven
|
|
Sp. Gravity
|
2.9-3.4
|
|
Form
|
Dendritic
|
|
Colour
|
Iron black
|
|
Luster
|
Metallic, dull
|
|
Steak
|
Bluish black
|
|
Hardness
|
6-6.5
|
|
Clevage
|
Perfect
|
|
Fracture
|
Uneven/Brittle
|
|
Sp. Gravity
|
4.4-5.1
|
|
Chemical composition
|
MnO2
|
|
Form
|
Euhedral
|
|
Colour
|
Brass yellow
|
|
Luster
|
Metallic
|
|
Steak
|
Greenish black
|
|
Hardness
|
3.5-4
|
|
Clevage
|
Poor/indistinct
|
|
Fracture
|
Uneven
|
|
Sp. Gravity
|
4.1-4.3
|
|
Chemical composition
|
CuFeS2
|
|
Form
|
Tabular
|
|
Colour
|
White, Gray
|
|
Luster
|
Dull, Earthy
|
|
Streak
|
Usually white but iron stain can discolour
|
|
Hardness
|
1-3
|
|
Cleavage
|
None
|
|
Fracture
|
Irregular
|
|
Sp. Gravity
|
2-2.5
|
|
Chemical composition
|
Al(OH)3
|
|
Form
|
Micaceous, Lamellar
|
|
Colour
|
Black,Dark brown, Black
|
|
Luster
|
Vitreous to pearly
|
|
Steak
|
White to gray
|
|
Hardness
|
2.5-3
|
|
Cleavage
|
Perfect
|
|
Fracture
|
Uneven
|
|
Sp. Gravity
|
2.8-3.4
|
|
Form
|
Prismatic, massive
|
|
Colour
|
White, colourless, yellow
|
|
Luster
|
Vitreous, pearly
|
|
Streak
|
White
|
|
Hardness
|
6-6.5
|
|
Cleavage
|
Good to perfect
|
|
Fracture
|
Conchoidal
|
|
Sp. Gravity
|
2.6-2.8
|
|
Form
|
Foliated, Massive
|
|
Colour
|
Colourless, White
|
|
Streak
|
White
|
|
Hardness
|
2.5
|
|
Cleavage
|
Perfect
|
|
Fracture
|
Uneven
|
|
Sp. Gravity
|
2.7-3
|
|
Form
|
Foliated
|
|
Colour
|
Pale green, white, gray
|
|
Luster
|
Vitreous/pearly
|
|
Steak
|
White to pale green
|
|
Hardness
|
1
|
|
Cleavage
|
Perfect
|
|
Fracture
|
Uneven
|
|
Sp. Gravity
|
2.7-2.8
|
|
Chemical composition
|
Mg3Si4O10(OH)2
|
|
Form
|
Microcrystalline aggregate
|
|
Colour
|
Green, yellow, red
|
|
Luster
|
Waxy, dull
|
|
Streak
|
White
|
|
Hardness
|
6.5-7
|
|
Cleavage
|
None
|
|
Fracture
|
Conchoidal
|
|
Sp. Gravity
|
2.6
|
|
Chemical composition
|
SiO2
|
|
Form
|
Euhedral, Prismatic
|
|
Colour
|
Blue, Red, yellow
|
|
Luster
|
Vitreous/Adamantine
|
|
Streak
|
Colourless
|
|
Hardness
|
9
|
|
Cleavage
|
None
|
|
Fracture
|
Conchoidal/uneven
|
|
Sp. Gravity
|
3.9-4.1
|
|
Chemical composition
|
Al2O3
|
|
Form
|
Dodecahedral
|
|
Colour
|
Red, Yellow
|
|
Luster
|
Vitreous
|
|
Steak
|
Colourless
|
|
Hardness
|
6.5-7.5
|
|
Cleavage
|
None
|
|
Fracture
|
Conchoidal
|
|
Sp. Gravity
|
3.5-4.3
|
|
Form
|
Massive, Granular
|
|
Colour
|
Olive green
|
|
Luster
|
Vitreous
|
|
Steak
|
Colourless
|
|
Hardness
|
6.5-7
|
|
Cleavage
|
Poor
|
|
Fracture
|
Conchoidal
|
|
Sp. Gravity
|
3.2-3.4
|
|
Chemical composition
|
(Mg,Fe)2SiO4
|
|
Form
|
Massive, Granular
|
|
Colour
|
White, Purple, Green
|
|
Luster
|
Vitreous
|
|
Streak
|
White
|
|
Hardness
|
4
|
|
Cleavage
|
Perfect
|
|
Fracture
|
Sub-conchoidal
|
|
Sp. Gravity
|
3.2
|
|
Chemical composition
|
CaF2
|
|
Form
|
Tabular, Massive
|
|
Colour
|
White, Colourless, Gray
|
|
Luster
|
Vitreous to Pearly
|
|
Streak
|
White
|
|
Hardness
|
2
|
|
Cleavage
|
Perfect
|
|
Fracture
|
Uneven
|
|
Sp. Gravity
|
2.3
|
|
Chemical Composition
|
CaSO4.2H2O
|
|
Form
|
Prismatic,Blocky
|
|
Colour
|
Colourless, Green, White
|
|
Luster
|
Vitreous to pearly
|
|
Streak
|
White
|
|
Hardness
|
6
|
|
Cleavage
|
Perfect
|
|
Fracture
|
Conchoidal
|
|
Sp. Gravity
|
2.6
|
|
Chemical composition
|
KAlSi3O8
|
|
Form
|
Prismatic
|
|
Colour
|
Various, balck, brown, green
|
|
Luster
|
Vitreous
|
|
Steak
|
White
|
|
Hardness
|
7-7.5
|
|
Cleavage
|
Poor/indistinct
|
|
Fracture
|
Conchoidal
|
|
Sp. Gravity
|
2.9-3.3
|
|
Form
|
Massive, Rhombohedron
|
|
Colour
|
White, Colourless,Gray
|
|
Luster
|
Vitreous
|
|
Streak
|
White
|
|
Hardness
|
3
|
|
Cleavage
|
Perfect
|
|
Fracture
|
Conchoidal
|
|
Sp. Gravity
|
2.7
|
|
Chemical composition
|
CaCO3
|
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