Mineral description : Calcite

Calcite with a thin line of some sulphide crystals, from Dorotea.
Clear calcite from unknown locality, showing double refraction in calcite
Calcite vein from Bergfors, Alnö-area.
White and red calcite with green fuchsite from Fauske, Norway.
Blue calcite from Ihalainen, Finland.
Yellow calcite from Crete, Greece.

Mineral class Carbonates : Calcite group.
Chemical formula CaCO3
Crystal system Trigonal.
Habitus Calcite is the mineral that shows the most various types of crystals. In my mind is the number of 137 different crystal forms, but I'm not shure about it. Anyone who knows?
Most common forms are tabular, sharp and stubby rhomboedric, prismatic an scalenoedric (dogtooth spar).
Calcite also occur as fibric aggregates, as coarse to fine grained aggregates or stalactitic.
Cleavage Perfect rhomboedric in three planes, subconchoidal fracture.
Hardness 3
Density 2.7
Color usually colorless, but nuances in blue, yellow, green, red, violet, even black and opaque.
Streak White to grayish.
Luster Vitreous to pearly or dull.
Description .
Occurance Calcite is the main ingredience of limestone rocks. It is also the mineral that builds up stalagmites in caves. Calcite is also a common mineral in hytdrothermal veins. Calcite can also occur in some eruptive rocks (Alnö), but only in the depth, since it is not stable at athmospheric pressure as a melt.
Associates .
Notes Reacts violently with hydrochloric acid.
Double refractive. Clear calcite is called Iceland spar, since it was mined there.
Often flourescent, especially when contaminated by manganeese.
Locations A very common mineral Crystals of calcite is also common, for example at
  • Storstrecks mine, Hofors, Gästrikland.
  • Åstorps makadambrott, Hälsingborg.
  • Grängesbergs mine.
  • Gräsbergs mine, Ludvika.
  • Hesselkulla mine, Närke.
  • Bölets mine, Karlsborg.
  • At Visby and Hoburgen, Gotland.
  • Rönnarp, Skåne.
  • Dylta, Närke.
  • Smålands Taberg.
  • Limestone mines at the Siljansringen.
  • At the manganese mines in Värmland ( especially Nordmark ).
  • Drömgruvans quarts quarry, Kolmorden.

To carbonates index.
Mineral group index.
Main index.

If you have some questions, suggestions or comments you are welcome to write me a line or two.


axelsson@acc.umu.se
To my homepage.
Last changed : 1998-05-09