Talc's related minerals

Talc ores differ according to their mineralogical composition, i.e. the type and proportion of associated minerals present (see diagram opposite). Although talc is often found with other minerals such as carbonates, the most common related mineral is chlorite. Chlorites (from the Greek khlôros meaning green) are present in varying proportions in several Luzenac deposits (from 2% to 50%). They are structurally and chemically very similar to talc (talc is a hydrated magnesium silicate and chlorite a hydrated magnesium and aluminum silicate). Each type of chlorite is determined by its aluminum and iron contents. Like talc, chlorites are soft, lamellar and organophilic (having an affinity with organic substances). However, they are a little more reactive than talc and more hydrophilic.

Chlorite is a hydrated magnesium and aluminum silicate with the chemical formula (Mg_6-x-y Fe_y Al_x) O₁₀ (OH)₈

As the diagram illustrates, there are many types of talc (each loop represents a different talc deposit).

Click to enlarge diagram