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Wollastonite  (Wollastonite-1A or Wollastonite-1T)
Current inventory:  0 gems
 

  
Wollastonite is named after William Hyde Wollaston (1766-1828), English chemist and mineralogist who discovered palladium (1804) and rhodium (1809) and invented the reflecting goniometer (1809) and the camera lucida (1812).

Discovered in 1818.   IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

CaSiO₃

Calcium Silicate

Molecular Weight:

116.16 gm

Composition:

Calcium

34.50 %

Ca

48.28 %

CaO

Silicon

24.18 %

Si

51.72 %

SiO₂

Oxygen

41.32 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/F.18-10

Nickel-Strunz 10th Ed. ID:

9.DG.05

9 : SILICATES (Germanates)
D : Inosilicates
G : Inosilicates with 3-periodic single and multiple chains

Related to:

Wollastonite Group. Polytypes: Wollastonite-1A, Wollastonite-2M, Wollastonite-3A, Wollastonite-4A, Wollastonite-5A, Wollastonite-7A.

Varieties:

Edelfarse, Manganoparawollastonite

Synonyms:

Aedelforsite (of Beudant), Gillebachite, Gillebäckite, Gjellebäckite, Grammite, Okenite (of Rink), Parawollastonite, Rivaite, Tabular Spar, Vilnite, Wollastonite (of Léman)

Crystal Data

Crystallography:

Triclinic - Pinacoidal

Crystal Habit:

Crystals tabular || {100} or {001}, or short to long prismatic, to 20 cm. Commonly cleavable, parallel fibrous, or compact, massive.

Twinning:

Common; twin axis [010], composition plane {100}.

Physical Properties

Cleavage:

{100} perfect; {001} and {102}, good; (100) ^ (001) =84.5°

Fracture:

Irregular/Uneven

Tenacity:

Brittle

Moh's Hardness:

4.5 - 5.0

Density:

2.86 - 3.09 (g/cm³)

Luminescence:

Some speciments are Fluorescent; SW UV = bright orange. May exhibit yellow catholuminescence.

Radioactivity:

Not Radioactive

Optical Properties

Color:

White, Colorless, Brown, Red, Yellow, pale Green; Colorless in thin section.

Transparency:

Transparent to Translucent

Luster:

Vitreous, Pearly on cleavages

Refractive Index:

1.615 - 1.662  Biaxial ( - )

Birefringence:

0.0140 - 0.0160

Dispersion:

Weak to Distinct; r > v

Pleochroism:

None

Occurances

Geological Setting:

Common in thermally metamorphosed siliceous carbonates, the intruding igneous rock, and skarn deposits along their contact; also in some alkalic igneous rocks and carbonatites.

Common Associations:

Calcite, Grossular, Diopside, Vesuvianite, Akermanite, Merwinite, Larnite, Spurrite

Type Locality:

n/a

Year Discovered:

1818

View mineral photos:

Wollastonite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Wollastonite is a fairly common silicate mineral with no unusual elements in its chemitry although some specimens, especially those from Franklin, New Jersey, do exhibit bright orange fluorescence under shortwave UV light. Wollastonite is primarily used as an important constituent in refractory ceramics (those ceramics that are resistant to heat) such as refractory tile and as a filler for paints. Cabochons created from material from Franklin, New Jersey are very collectible for their Fluorescent properties.

Wollastonite is named for the English chemist and mineralogist W. H. Wollaston (1766 - 1828). Its actual mineralogical name is Wollastonite-1T. The 1T is for the Triclinic symmetry of the most common and first described Wollastonite mineral. The reason the 1T is needed is to distinguish it from the much more rare Wollastonite-2M, also known as Parawollastonite. Parawollastonite is Monoclinic. These minerals are polymorphs which means that they have the same chemistry, CaSiO3, just different structures (poly means many and morph means shape). There are actually several other rare and obscure polymorphs of CaSiO3 and are given the proposed names of Wollastonite-3T, Wollastonite-4T, Wollastonite-5T and finally Wollastonite-7T. All specimens named just Wollastonite are most likely Wollastonite-1T.

Wollastonite is a widely distributed mineral; some prominent localities are: in Romania, at Dognecea and Csiklova, Banat. In Italy, at Sarrabus, Sardinia, and from Monte Somma and Vesuvius, Campania. In Ireland, at Dunmorehead, Mourne Mountains, and Scawt Hill, near Larne, Co. Antrim. From Kongsberg, Norway. At Göckum, Sweden. In Germany, at Harzburg, Harz Mountains, and Auerbach, Odenwald, Hesse. In the USA, at Natural Bridge and Diana, Lewis County, New York; from Crestmore, Riverside County, and Darwin, Inyo County, California; in a large deposit two miles southeast of Gilbert, Esmeralda County, Nevada. In Canada, at Oka and Asbestos, Quebec; at Outlet Post, Leeds County, Ontario. From Pichucalo, Chiapas, and in the Pilares deposit, 55 km north of Hermosillo, Sonora, Mexico. At Hiiagiyama, Ibaragi Prefecture; Ishiyamadera, Shiga Prefecture; and Kushiro, Hiroshima Prefecture, Japan. Large crystals from Belafa, Madagascar.
 

  
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