Soapstone, or steatite, is another of the metamorphic rocks, being derived from plutonic rocks or lavas containing a mineral known as olivine. It is grey or greenish in colour and is composed mainly of talc, carbonate minerals and chlorite.
As its name implies, soapstone is soft and can be shaped with a knife. This is due to the presence of talc, which is a very soft mineral. This workability together with its good heat diffusion properties has made it a popular material for the construction of ovens and fireplaces. It was also used extensively in the façades of buildings in the late 19th and early 20th centuries, and has begun to come back into favour for this purpose in recent times.