Properties of Soapstone

Varieties of carving stone often referred to as Soapstone.

Steatite is a massive and compact rock containing more than 90 % talc. The remainder consists of silicates (chlorite) and/or magnesium carbonates.

Soapstone is a massive, soft, impure talc rock that contains variable proportions of magnesian carbonates (dolomite and/or magnesite), serpentine, chlorite, tremolite and magnetite.

Pyrophyllite is a hydrated aluminum silicate. In contrast to talc, pyrophyllite is the product of hydrothermal alteration of felsic igneous rocks (rhyolite, dacite) and schists derived from metamorphosed volcanic ash. Nonetheless, its physical properties are identical to those of talc, and it therefore provides an ideal substitute for talc in a number of industrial applications.

Breunerite is ferroan (iron-rich) magnesite.

Soapstone is a metamorphic rock having a talc base ("metamorphic" means changing from one type of stone to another through time and pressure). It occurs as a secondary mineral formed as a result of the alteration of olivine, pyroxene,and amphibole. The purest talc is used commercially to make talcum powder. Soapstone can be distinguished by its' ease of carving, soapy feel, and vibrant colour, which is obtained by the associated minerals leaching into the talc.

Because of its malleability, it has been used as a carving material for centuries. Egyptians carved figures and bowls of soapstone to be put into the tombs of pharaohs. Soapstone seals of Indian origin have been found in Bahrain and Ur. Paleoeskimos were mining the stone to make bowls and lamps on the Baie Verte Peninsula 1600 years ago. Native American Indians throughout North America carved soapstone into ornamental pipes and bowls.

Soapstone is available world wide, the colour of soapstone varying according to location and the proximity of various mineral deposits in the area. Soapstone contains talc and chlorite. The parent rock is peridotite, probably with more water associated with it than in the formation of serpentine. Many minerals mix readily with soapstone, creating the hues and markings that intrigue the observer of a sculpture. I work in the dark green and black soapstone of the eastern townships of Quebec, but the colours vary throughout the continent and the world. In China there is pale green and pink soapstone some of which I have seen and used; in Russia and Alaska there is black soapstone. Montana produces a dendritic soapstone having the look of moss growing through the stone. Pyrite crystals (fool's gold) can also be found within the stone showing as golden flecks. Dolomite is the mineral that determines the hardness of the soapstone that I work on. Some stone can be very easy to work and other pieces extremely hard.

I often am asked about asbestos in soapstone. The question probably derives from the fact that talc and asbestos are part of the same metamorphic family of rocks and may often exist in the same area. . The serpentinized ultramafic rocks that host asbestos deposits may also contain talc and viceversa. If asbestos were present in the soapstone, the veins of asbestos would appear as cotton like and fibrous and are quite identifiable. For further geological information on the formation of soapstone (click here)

If you are really concerned, reputable talc quarries can furnish an analysis of the soapstone indicating the presence of asbestos, if it is present in the stone.

I obtain my stone from Les Pierres Stéatites Inc. at St. Pierre de Broughton, Quebec. They mine their stone by cutting and using wedges to break the stone from the wall of the quarry. The stone is then taken to the mill and cut into appropriate sizes for carving. Here is a pictorial of the process.

     For other occurences of talc in the province of Quebec, (click here)

If you have other questions, Email Me

The Old Broughton Soapstone Quarry


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