MEGASCOPIC IDENTIFICATION OF COMMON ROCK-FORMING MINERALS.

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COMPOSITION CaCO3
CRYSTAL SYSTEM HEXAGONAL
CRYSTAL FORM/HABIT RHOMBOHEDRAL CRYSTALS
COLOUR WHITE
LUSTRE VITREOUS
TRANSPARENCY TRANSLUCENT
STREAK WHITE
CLEAVAGE PERFECT
FRACTURE CONCHOIDAL
HARDNESS 3
SPECIFIC GRAVITY 2.5-2.8
DIAGNOSTIC PROPERTIES RHOMBOHEDRAL CRYSTALS, WHITE IN COLOUR, HARDNESS 3 WITH VITREOUS LUSTRE AND CONCHOIDAL FRACTURE.
OCCURRENCE AND ASSOCIATION OCCURS AS COMMON MINERAL, IN SEDIMENTS, ALTERED BASIC IGNEOUS ROCKS, IN VEINS, etc.,
NAME CALCITE

COMPOSITION  
CRYSTAL SYSTEM MONOCLINIC
CRYSTAL FORM/HABIT MASSIVE
COLOUR LIGHT PINK
LUSTRE VITREOUS
TRANSPARENCY OPAQUE
STREAK WHITE
CLEAVAGE PERFECT
FRACTURE UNEVEN
HARDNESS 6
SPECIFIC GRAVITY 2.5-2.8
DIAGNOSTIC PROPERTIES LIGHT PINK IN COLOUR, PERFECT CLEAVAGE, AND HARDNESS IS SIX
OCCURRENCE AND ASSOCIATION IT OCCURS AS AN ESSENTIAL CONSTITUENT OF ACID IGNEOUS ROCKS AND IS COMMON IN METAMORPHIC ROCKS.
NAME ORTHOCLASE FELDSPAR

COMPOSITION CaCO3
CRYSTAL SYSTEM HEXAGONAL
CRYSTAL FORM/HABIT RHOMBOHEDRAL CRYSTALS
COLOUR GREY
LUSTRE PEARLY
TRANSPARENCY OPAQUE
STREAK WHITE
CLEAVAGE PERFECT RHOMBOHEDRAL
FRACTURE CONCHOIDAL
HARDNESS 3.5-4.0
SPECIFIC GRAVITY 2.84-2.86
DIAGNOSTIC PROPERTIES RHOMBOHEDRAL CRYSTALS, GREY IN COLOUR, PEARLY LUSTRE, PERFECT CLEAVAGE, AND CONCHOIDAL FRACTURE.
OCCURRENCE AND ASSOCIATION IN SEDIMENTARY AND METAMORPHIC ROCKS
NAME DOLOMITE

COMPOSITION  
CRYSTAL SYSTEM HEXAGONAL
CRYSTAL FORM/HABIT MASSIVE
COLOUR WHITE
LUSTRE VITREOUS
TRANSPARENCY TRANSLUCENT
STREAK COLOURLESS
CLEAVAGE ABSENT
FRACTURE CONCHOIDAL
HARDNESS 7
SPECIFIC GRAVITY 2.5-2.8
DIAGNOSTIC PROPERTIES WHITE IN COLOUR, HARDNESS IS 7 WITH  CONCHOIDAL FRACTURE AND VITREOUS LUSTRE.
OCCURRENCE AND ASSOCIATION OCCURS IN ACID IGNEOUS ROCKS, MANY METAMORPHIC ROCKS, AS A VEIN STONE, IN SEDIMENTARY ROCKS, etc.,
NAME QUARTZ

COMPOSITION  
CRYSTAL SYSTEM MONOCLINIC
CRYSTAL FORM/HABIT TABULAR, FOLIATED
COLOUR PALE YELLOW
LUSTRE PEARLY
TRANSPARENCY TRANSPARENT
STREAK COLOURLESS
CLEAVAGE PERFECT
FRACTURE UNEVEN
HARDNESS 2.5-3.0
SPECIFIC GRAVITY 2.77-2.88
DIAGNOSTIC PROPERTIES TABULAR, FOLIATED HABIT, PALE YELLOW IN COLOUR, PEARLY LUSTRE AND PERFECT CLEAVAGE
OCCURRENCE AND ASSOCIATION OCCURS IN GRANITE PEGMATITE SCHIST
NAME MUSCOVITE

COMPOSITION  
CRYSTAL SYSTEM MONOCLINIC
CRYSTAL FORM/HABIT TABULAR, FOLIATED
COLOUR BLACK/DARK BROWN
LUSTRE PEARLY
TRANSPARENCY TRANSPARENT
STREAK COLOURLESS
CLEAVAGE PERFECT
FRACTURE UNEVEN
HARDNESS 2.5-3.0
SPECIFIC GRAVITY 2.8-3.2
DIAGNOSTIC PROPERTIES TABULAR, FOLIATED HABIT, BLACK/DARK BROWN IN COLOUR,  PEARLY LUSTRE, AND PERFECT CLEAVAGE
OCCURRENCE AND ASSOCIATION IN IGNEOUS ROCKS OF ALL KINDS AND IN MANY METAMORPHIC ROCKS.
NAME BIOTITE

COMPOSITION  
CRYSTAL SYSTEM MONOCLINIC
CRYSTAL FORM/HABIT MASSIVE
COLOUR WHITE
LUSTRE PEARLY
TRANSPARENCY OPAQUE
STREAK WHITE
CLEAVAGE PERFECT
FRACTURE UNEVEN
HARDNESS 1
SPECIFIC GRAVITY 2.58-2.83
DIAGNOSTIC PROPERTIES WHITE IN COLOUR WITH PEARLY LUSTRE, PERFECT CLEAVAGE, AND HARDNESS IS 1.
OCCURRENCE AND ASSOCIATION IN METAMORPHIC ROCKS RICH IN MAGNESIUM, ALSO OCCURS WITH SERPENTINE
NAME TALC

COMPOSITION  
CRYSTAL SYSTEM HEXAGONAL
CRYSTAL FORM/HABIT BARREL-SHAPED
COLOUR GREY
LUSTRE DULL
TRANSPARENCY OPAQUE
STREAK COLOURLESS
CLEAVAGE ABSENT
FRACTURE UNEVEN
HARDNESS 9
SPECIFIC GRAVITY 3.98-4.02
DIAGNOSTIC PROPERTIES GREY IN COLOUR WITH A BARREL-SHAPED FORM AND HARDNESS IS 9.
OCCURRENCE AND ASSOCIATION WIDELY OCCURS IN METAMORPHIC ROCKS, AS VEIN IN SOME IGNEOUS ROCKS.
NAME CORUNDUM

COMPOSITION  
CRYSTAL SYSTEM HEXAGONAL
CRYSTAL FORM/HABIT MASSIVE
COLOUR PALE GREEN
LUSTRE SUB VITREOUS
TRANSPARENCY TRANSLUCENT
STREAK COLOURLESS
CLEAVAGE IMPERFECT
FRACTURE UNEVEN
HARDNESS 7.5-8
SPECIFIC GRAVITY 2.5-2.8
DIAGNOSTIC PROPERTIES PALE GREEN IN COLOUR AND HARDNESS IS 7.5-8
OCCURRENCE AND ASSOCIATION IN ACID IGNEOUS ROCKS, PEGMATITES. GEM VARIETIES ARE EMERALD AND AQUAMARINE
NAME BERYL

COMPOSITION  
CRYSTAL SYSTEM ISOMETRIC
CRYSTAL FORM/HABIT DODECAHEDAL CRYSTALS
COLOUR DEEP RED
LUSTRE DULL
TRANSPARENCY OPAQUE
STREAK COLOURLESS
CLEAVAGE ABSENT
FRACTURE UNEVEN
HARDNESS 7-7.5
SPECIFIC GRAVITY 3.5-4.3
DIAGNOSTIC PROPERTIES WELL-DEFINED CRYSTALS OF DODECAHEDRON, DEEP RED IN COLOUR AND HARDNESS IS 7-7.5
OCCURRENCE AND ASSOCIATION COMMON MINERAL IN METAMORPHIC SCHIST AND AND ROCK
NAME GARNET

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