Black soapstone is classified as a soft, black, metamorphic rock. Soapstone is also called steatite or soaprock at times. Metamorphic rocks, such as this one, are formed from one type of rock through a physical change over time. The changes that produce this category of rocks are dynamothermal, or heat-based, and metasomatism, which involves a change caused by fluids and heat in combination. Although heat is involved in the formation of soapstone from a protolith, or origin rock, it is never formed by melting.
Black soapstone is also described as a talc-schist. It contains large amounts of the mineral talc, as well as quantities of the element magnesium. The ending syllable “schist” indicates that this rock is a member of a group of metamorphic rocks that typically contain significant amounts of minerals like talc, micas, hornblende, graphite and chlorite.
Schists are also known for having mineral grains that break off easily into flakes or slabs. Black soapstone often shares this characteristic to a certain extent. It is distinguished from other similar stones, however, by its “soapy” feel. Soapstone, including black soapstone, is found across the globe, making it readily available for everything from carvings to kitchen counter tops and tiles.
Black soapstone’s color is derived from a number of different factors. These factors include the presence of various chemicals and minerals that may have interacted long ago during the rock’s formation. No single cause or component can account for the colors found in any type of soapstone. When cut, black soapstone will react with the oxygen in the air and change from its original gray to a darker charcoal color.
Black soapstone’s characteristics make it ideal for carving. Some bowls and carvings date back as far as 1600 years ago. It is one of the softest, most malleable stones in existence anywhere. Molds that are used for casting soft metals are often made of soapstone, due in part to its ability to absorb and dissipate heat evenly.
Soapstone is used very frequently for counter tops; with black soapstone being a popular choice. The color and texture of all types of the stone is why it is such a popular choice. Marks and scratches to counter tops can be fixed by carefully sanding the affected area and applying mineral oil after that. Applying mineral oil can also serve to deepen the existing color or make the veins in the rock stand out more prominently.