TALC
Talc is a magnesium hydroxysilicate mineral, Mg3Si4O10(OH)2. Talc is the softest mineral on the Mohs
Hardness Scale (H≡1). It has a pearly, nonmetallic luster, usually
has a whitish color, whitish streak, and has a slick, soapy feel. Talc is
moderately common in some low-grade to intermediate-grade metamorphic rocks
such as talc schist, soapstone, and steatite.
Talc
(5.0 cm across)