Talc
Talc (from the Arabic talk) is a silicate mineral, a type of clay. It is the standard for grade 1 in the Mohs scale of mineral hardness. A fingernail can easily scratch it. Talc is composed of hydrated magnesium silicate with the chemical formula Mg3Si4O10(OH)2. Talc and pyrophyllite are very similar, but pyrophyllite may be slightly harder.
Talc has a greasy feel and a translucent, soapy look. In loose form, it is the widely used substance known as talcum powder. Steatite, also called soapstone, is a rock with a lot of talc.
Talc Media
- Talcblock
Talcum powder on black construction paper for contrast.
The structure of talc is composed of Si2O5 sheets with magnesium sandwiched between sheets in octahedral sites.
View of tetrahedral sheet structure of talc. The apical oxygen ions are tinted pink.
View of trioctahedral sheet of talc. Yellow spheres are hydroxyl; blue are magnesium. Apical oxygen binding sites are white.
Talc crystal viewed along the [100] axis, looking along the layers of the crystal
