Sentence:  For example, Montana <WSD>talcs</WSD> approximate the theoretical composition, while California <WSD>talcs</WSD> often contain calcite (CaCO<sub>3</sub>) and dolomite (CaCO<sub>3</sub> • MgCO<sub>3</sub>). 
Meaning of the word marked with <WSD> tags:  A soft mineral, composed of hydrated magnesium silicate, that has a soapy feel and a greenish, whitish, or grayish color, and usually occurs in foliated masses.