• Chemistry: CaSiO3 , Calcium Silicate.
  • Class: Silicates
  • Subclass: Inosilicates
  • Group: Pyroxenoid
  • Uses: In ceramics, as a paint filler and as mineral specimens.
  • Specimens

Wollastonite is a common mineral in skarns or contact metamorphic rocks. Skarns can sometimes produce some wonderfully rare and exotic minerals with very unusual chemistries. However, wollastonite has no unusual elements in its chemistry and it is somewhat common and not considered very exotic among collectors. Wollastonite forms from the interaction of limestones, that contain calcite, CaCO3, with the silica, SiO2, in hot magmas. This happens when hot magmas intrude into and/or around limestones or from limestones chunks that are broken off into the magma tubes under volcanoes and then blown out of them. It forms by the following formula:

CaCO3 + SiO2 ----> CaSiO3 + CO2

Although not an "exotic" mineral, wollastonite has its uses. It is an important constituent in refractory ceramics (those ceramics that are resistant to heat) such as refractory tile and as a filler for paints. It is easily mined in some places where it is the major component of the metamorphosed rock. Mineral specimens can be interesting with their fibrous habit, pearly luster and some specimens, especially those from Franklin, New Jersey, will fluoresce.

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.


  • Color is typically white, colorless or gray.
  • Luster is vitreous or dull to pearly on cleavage surfaces.
  • Transparency: Crystals are generally translucent and rarely transparent.
  • Crystal System is triclinic; bar 1
  • Crystal Habits include rare tabular crystals but more commonly massive in lamellar, radiating, compact and fibrous aggregates.
  • Cleavage is perfect in two directions at near 90 degrees forming prisms with a rectangular cross-sections. A third direction of cleavage is only good to fair and overall cleavage fragments are elongated splinters.
  • Fracture is splintery to uneven.
  • Hardness is 5 - 5.5.
  • Specific Gravity is approximately 2.8 - 2.9 (average for translucent minerals)
  • Streak is white.
  • Other Characteristics: Soluble in hydrochloric acid and some specimens will fluoresce.
  • Associated Minerals are garnets such as grossular and andradite, vesuvianite, diopside, tremolite, epidote, various plagioclase feldspars and of course calcite.
  • Notable Occurrences include Willsboro and other sites in New York, Texas, California and also Franklin, New Jersey, USA; the volcano Monte Somma, Vesuvius, Italy; Perheniemi, Finland; Banat, Rumania; Saxony, Germany; Chiapas, Mexico; Greece; China; Ontario and at the Jeffrey Mine, Asbestos, Quebec, Canada and Tremorgio, Switzerland.
  • Best Field Indicators are crystal habit, cleavage, solubility in HCl, fluorescence if present, softness and environment of formation.
(hover for more info)
WOLLASTONITE specimen wll-1
$ 22.00
Dims: 2.4" x 1.3" x 0.9" (6.1 x 3.3 x 2.3 cm)
Wt: 1.37 oz. (38.9 g)
Lake Bonaparte, Lewis County, New York, U.S.A.
This simple specimen consists of a few intersecting Wollastonite crystals. These crystals do not appear to be complete, as they have no discernable terminations. Its triclinic form is difficult to determine due to its very splintery fracture. The crystals have a white coloration and a pearly luster that almost appears silky, and is only moderately translucent. Though Wollastonite often shows a strong fluorescence, these crystals do not.
no photo
wll-1 ($ 22.00)
Lake Bonaparte, Lewis County, New York, U.S.A.
WOLLASTONITE specimen wll-2
$ 25.00
Dims: 2.6" x 1.5" x 1.0" (6.6 x 3.8 x 2.5 cm)
Wt: 1.70 oz. (48.2 g)
Lake Bonaparte, Lewis County, New York, U.S.A.
Like the previous specimen, this piece consists of several partial triclinic crystals that seem to be made up of many parallel, tightly packed fibers or blades. There is only one small projection that seems to consist of a complete crystal on one end of the specimen. Other than that, there are no other intact terminations. The material has a bright, white coloration and a pearly luster, and is translucent. There is no other material present on the specimen.
no photo
wll-2 ($ 25.00)
Lake Bonaparte, Lewis County, New York, U.S.A.
WOLLASTONITE specimen wll-3
$ 90.00
Dims: 7.5 x 4.9 x 2.5" (19.1 x 12.4 x 6.4 cm)
Wt: 4 lbs., 3.3 oz. (1.907 kg)
Sterling Hill Mine, Ogdensburg, New Jersey, U.S.A.
A considerable amount of massive Wollastonite is embedded in this large cabinet specimen. However, it is essentially indiscernable from the milky-white calcite matrix- the only way to clearly see it is by bathing the piece in shortwave ultraviolet light, which will cause the Wollastonite to glow a noticeable orange-yellow coloration. The calcite glows also, but its color is a deeper red-orange, and it glows only dimly. Many tiny franklinite grains or crystals are also embedded in the piece- these are easy to see because they are black in color and do not glow.
no photo
wll-3 ($ 90.00)
Sterling Hill Mine, Ogdensburg, New Jersey, U.S.A.
WOLLASTONITE specimen wll-4
$ 32.00
Dims: 5.4 x 2.8 x 2.1" (13.5 x 7.1 x 5.4 cm)
Wt: 1 lb., 2.5 oz. (521 g)
Sterling Hill Mine, Ogdensburg, New Jersey, U.S.A.
This cabinet-sized specimen consists of a massive, white calcite matrix in which is embedded a sizable amount of massive Wollastonite. The Wollastonite is all but invisible against the calcite when viewed under white light, but shortwave ultraviolet light will cause it to glow with a maize-yellow (yellow with a hint of orange) color. A small amount of willemite is also present, with its classic green glow, and the calcite glows only in a few places, and only with a dim orange color, at that.
no photo
wll-4 ($ 32.00)
Sterling Hill Mine, Ogdensburg, New Jersey, U.S.A.
WOLLASTONITE specimen wll-5
$ 32.00
Dims: 4.4 x 2.8 x 1.9" (11.2 x 7.1 x 4.8 cm)
Wt: 14.7 oz. (416 g)
Sterling Hill Mine, Ogdensburg, New Jersey, U.S.A.
Very many small patches of massive Wollastonite are embedded in the massive calcite matrix of this small cabinet specimen. These small spots are essentially undefinable under white light, but when the piece is exposed to shortwave UV light, the Wollastonite emits a rather bright, maize-yellow coloration. It is accompanied by a very small amount of willemite, which also shows its bright green color, but the calcite that forms the matrix is almost inert with respect to fluorescence.
no photo
wll-5 ($ 32.00)
Sterling Hill Mine, Ogdensburg, New Jersey, U.S.A.


Copyright ©1995-2023 by Amethyst Galleries, Inc.