කුරුවින්ද
General
CategoryOxide mineral – Hematite group
රසායනික සූත්‍රයAluminium oxide, Al2O3
Strunz classification04.CB.05
Dana classification4.3.1.1
Crystal symmetryTrigonal (32/m)
Unit cella = 4.75 Å, c = 12.982 Å; Z=6
Identification
පාට / පැහැයColorless, gray, brown; pink to pigeon-blood-red, orange, yellow, green, blue to cornflower blue, violet; may be color zoned, asteriated mainly grey and brown
Crystal habitSteep bipyramidal, tabular, prismatic, rhombohedral crystals, massive or granular
Crystal systemTrigonal (Hexagonal Scalenohedral)
Symbol (32/m)
Space group: R3c
TwinningPolysynthetic twinning common
CleavageNone – parting in 3 directions
FractureConchoidal to uneven
Mohs scale hardness9 (defining mineral)[1]
LusterAdamantine to vitreous
StreakWhite
DiaphaneityTransparent, translucent to opaque
Specific gravity3.95–4.10
Optical propertiesUniaxial (–)
Refractive indexnω = 1.767–1.772
nε = 1.759–1.763
PleochroismNone
Melting point2044 °C
FusibilityInfusible
SolubilityInsoluble
Alters toMay alter to mica on surfaces causing a decrease in hardness
Other characteristicsMay fluoresce or phosphoresce under UV
References[2][3][4][5]
Major varieties
SapphireAny color except red
RubyRed
EmeryBlack granular corundum intimately mixed with magnetite, hematite, or hercynite
  1. "Moh's scale of hardness". Collector's corner. Mineralogical Society of America. සම්ප්‍රවේශය 10 January 2014.
  2. Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W. and Nichols, Monte C., ed. (1997). "Corundum". Handbook of Mineralogy (PDF). Vol. III(Halides, Hydroxides, Oxides). Chantilly, VA, US: Mineralogical Society of America. ISBN 0962209724.{{cite book}}: CS1 maint: multiple names: editors list (link)
  3. Corundum. Mindat.org
  4. Corundum. Webmineral
  5. Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., Wiley, pp. 300–302 ISBN 0-471-80580-7
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