Calcite

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Calcite
Calcite-67881.jpg
General
CategoryCarbonate mineral
Formula
(repeatin unit)
CaCO3
Strunz clessification05.AB.05
Creestal seestemTrigonal hexagonal scalenohedral (32/m), Space Group (R3 2/c)
Space groupTrigonal 32/m
Unit cella = 4.9896(2) Å, c = 17.0610(11) Å; Z=6
Identification
ColourColourless or white; can be gray, yellae or green.
Creestal habitCrystalline, granular, stalactitic, concretionary, massive, rhombohedral.
TwinninCommon bi fower twin laws
CleavagePerfect on [1011] three directions wi angle o 74° 55'[1]
FracturConchoidal
TenacityBrickle
Mohs scale haurdness3 (definin mineral)
SkinkleVitreous tae pearly on cleavage surfaces
StreakWhite
DiaphaneityTransparent tae translucent
Speceefic gravity2.71
Optical propertiesUniaxial (-)
Refractive indexnω = 1.640 – 1.660 nε = 1.486
Birefringenceδ = 0.154 – 0.174
SolubilitySoluble in dilute acids
Ither chairacteristicsMey fluoresce reid, blae, yellae, an ither colours unner aither SW an LW UV; phosphorescent
References[2][3][4]

Calcite is a carbonate mineral an the maist stable polymorph o calcium carbonate (CaCO3). The ither polymorphs is the meenerals aragonite an vaterite. Aragonite will chynge tae calcite at 380–470 °C,[5] an vaterite is even less stable.

References[eedit | eedit soorce]

  1. Klein, Cornelis and Cornelius S. Hurlbut, Jr., Manual of Mineralogy, Wiley, 20th, 1985, p. 329 ISBN 0-471-80580-7
  2. Mineral Data Publishers
  3. Calcite at Mindat
  4. Calcite at Webmineral
  5. S.Yoshioka and Y.Ktiano. "Transformation of aragonite to calcite through heating" (PDF). DTA -TG study. Geochemical Journal Vol.19. Retrieved 31 March 2011.