WHENCE TALC?
Talc is mined from Talc-bearing metamorphic rock. Within this rock, bodies of Talc can often range in thickness from tens of meters to over 100 meters. How the Talc formed within the rock and the nature of the rock itself determines the quality of the Talc.
Talc is one of the many minerals that are deposited in more than one way. Many minerals are deposited by hydrothermal earth activities. In cases of deposits when hydrothermal activities take place, the deposits are usually classified according to the parent rock from which they derived.
Talc has at least four types of “Talc
deposits”.
1. The first type of deposit is derived from
Magnesium Carbonates. Found in ancient metamorphosed carbonate sequences, this Talc deposit is usually the purest form
of Talc. It is mostly white and
provides almost 50% of the world's Talc
production. These deposits, which form the majority of large deposits to be
found in the U.S. today, produce some of the purest and whitest Talc.
2. The second type of Talc deposits are made from Serpentines, which provide 40% of the world's Talc production. This type of Talc comes from the metamorphosis of Serpentinite into a mixture of reactional Magnesium Carbonates and Talc, forming the ore commonly known as Soapstone." This deposit formation of Talc is usually grey and does not serve much commercial use. Soapstone itself is often used domestically in countertops and the surrounds of fireplaces and stoves.
3. The third type of Talc deposit is derived from Alumino-silicate rock. Only about 10% of this type of Talc deposit is mined to meet the world's Talc supplies. It is found mostly in a gray crude ore and alongside many other hydrothermal minerals. This type of Talc is found at Trimouns in the French Pyrenees.
4. Finally, Talc is deposited from magnesium sedimentary deposits. This type of deposit is not mined currently and does not bring good economical value. A Talc deposit can be formed by direct transformation of magnesium clay. This Talc deposit can be found in many locations. The wide diversity of Talc deposits has given rise to a massive array of ores and product grades of Talc for human uses.
