Mineral description : Thaumasite

Thaumasite from Viscaria, Sweden.
It's so shiny white it's spoiling the picture.

Mineral class Silicates : Nesosilicates :
Chemical formula Ca6Si2(CO3)2(SO4)2(OH)12·24H2O
Crystal system Hexagonal.
Habitus As massive aggregates or radiating crystal aggregates. Also as acicular crystals.
Cleavage Poor, uneven fracture.
Hardness 3.5
Density 1.9
Color White or colorless.
Streak White
Luster Vitreous.
Description This mineral is as close to water as you could get.
Occurance  
Associates  
Notes Type locality : Bjelkesgruvan, Åreskuta, Jämtland, Sweden.
Locations A not so common mineral
  • Bjelkesgruvan, Åreskutan, Jämtland, Sweden. Filling up fractures.
  • Skottvångs gruva, Gåsingen. Together with apophyllite.
  • Långban, Värmland. As radiating white suns in fractures in jaspis together with apophyllite.
  • Viscaria, Kiruna, Lappland. As thick snow white aggregates of thin crystals.
    (It was actually mistaken for snow when it first appeared on the dump pile, but it never melted in the spring!)

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

axelsson@acc.umu.se
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Last changed : 2000-01-01