Mineral description : Wollastonite

Wollastonite from Svartsång mining field, Filipstad. Sample size 10 cm.

Wollastonite from Ihalainen, Finland.
A quartz vein in calcite with wollastonite in the contact zone.

Mineral class Silicates : Inosilicates : wollastonite group.

Chemical formula Ca₃(Si₃O₉)

Crystal system Triclinic

Habitus Usually as fibric radial masses or massive.

Cleavage Perfect along the crystal (84 and 96 degrees), forms splinters.

Hardness 4.5-5

Density 2.8-2.9

Color Usually white, sometimes weak pink or green.

Streak White.

Luster Glas, silky or pearly on fresh cleavages.

Description

Occurance Wollastonite is formed by magnesium free calcite which reacts with silicate solutions. Often found in lime stone deposits transformed by silicone rich solutions.

Associates Calcite, diopside, tremolite, garnet( grossular) and vesuvian

Notes Sticky surface, often fluorescent in UV, decomposes to silicagel in HCl.
Separates from chrysotil in hardness and tremolite resists the acid.

Locations Not so common in Sweden, but can be found in a number of Swedish lime mines.

Tennbergs and Wikströms mine outside Ludvika.
Älgfallet outside Kopparberg.
Gåsgruvan lime mine, Persberg.
Änggruvan, Nordmark.
Tennbetgets lime mine, Grängesberg.
Hönsarvsbergets lime mine, Borlänge.
Alnön, Sundsvall.
Ihalainen limestone quarry, Lappenranta, Finland. Up to 25% of the rock.

To silicate 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

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Last changed : 1998-03-07

Mineral class	Silicates : Inosilicates : wollastonite group.
Chemical formula	Ca₃(Si₃O₉)
Crystal system	Triclinic
Habitus	Usually as fibric radial masses or massive.
Cleavage	Perfect along the crystal (84 and 96 degrees), forms splinters.
Hardness	4.5-5
Density	2.8-2.9
Color	Usually white, sometimes weak pink or green.
Streak	White.
Luster	Glas, silky or pearly on fresh cleavages.
Description
Occurance	Wollastonite is formed by magnesium free calcite which reacts with silicate solutions. Often found in lime stone deposits transformed by silicone rich solutions.
Associates	Calcite, diopside, tremolite, garnet( grossular) and vesuvian
Notes	Sticky surface, often fluorescent in UV, decomposes to silicagel in HCl. Separates from chrysotil in hardness and tremolite resists the acid.
Locations	Not so common in Sweden, but can be found in a number of Swedish lime mines. Tennbergs and Wikströms mine outside Ludvika. Älgfallet outside Kopparberg. Gåsgruvan lime mine, Persberg. Änggruvan, Nordmark. Tennbetgets lime mine, Grängesberg. Hönsarvsbergets lime mine, Borlänge. Alnön, Sundsvall. Ihalainen limestone quarry, Lappenranta, Finland. Up to 25% of the rock.