Lathe turning, a process mostly associated with woodcarving, is also a manufacturing technique used in stone carving to make bowls, cups and vases. Performed by pressing metal tools against a turning block of stone, lathe turning typically requires soft stones. Measured by the Mohs scale, which rates stone hardness from 1 to 10, soft stones used most frequently to make vases rate from 1 to 4, and include soapstone, alabaster, onyx and limestone.
The most common and softest type of stone used for turned vases is soapstone, technically called steatite. Composed mainly of mineral talc, soapstone has a Mohs hardness rating of 1 and is characteristically easy to carve. Mined all over the world, soapstone is available in a variety of colours, including white, brown, grey-green, red and black. Archaeological evidence of soapstone dates back thousands of years in the art of the Near East and Egypt.
Another lathe-turned soft stone is alabaster. Now used as a descriptive for a perfect complexion, alabaster is typically white with interspersed soft hues of pink. With a Mohs hardness rating of 2 or less, alabaster is a soft stone that is both easily manipulated and susceptible to scratching. Like soapstone, evidence of lathe-turned alabaster vases date back to ancient Egypt, and is prevalent in both western Mediterranean regions and the Middle East.
With a Mohs scale hardness of 3, onyx is another type of soft stone used to create lathe-turned vases. Often thought of as being a black stone, onyx is actually available in a variety of colours, including green, yellow, red and brown. Also referred to as semi-precious agate, onyx is a carbonate sedimentary rock, formed by the introduction of thermal water to calcites, such as limestone. Capable of holding a high gloss shine, onyx vases are best for holding non-acid dry goods and flowers.
Further up the Mohs hardness scale with a rating of 3 to 4, limestone is another type of rock used for turned vases. A sedimentary stone, limestone formed millions of years ago by the layering and compacting of oceanic sedimentation in regions once submerged under shallow seas. Other types of limestone used for carving include flowstone and banded travertine. Banded travertine, a crystalline form of limestone, is a visually stunning stone, with banded layers ranging from orange and brown to green and white.