White Talc (7) Raw Minerals Stones Rocks Collecting

Description

Origin : Italy (Piemonte)

White Talc 301-400 gr - cm 7-10 Raw Minerals Stones Rocks for Collection.

Talc is a mineral, a magnesium phyllosilicate, very widespread on Earth and whose use has been known since ancient times. The name comes from the Arabic talq and can be abbreviated to TLC. The crystalline structure of talc is like that of pyrophyllite with the only difference that the octahedral sites of the lattice are occupied by magnesium instead of aluminum; therefore, talc is a trioctahedral phyllosilicate.
In its chemical composition aluminum, titanium, ferrous iron and manganese may sometimes be present, which replace silicon and magnesium respectively.
Talc is a mineral of secondary origin, present both in eruptive rocks and, frequently, in metamorphic ones, of which it can also be the main component: in this case we speak of talcoscisti.
Talc is found in flakes, small crystals, compact scaly or granular masses, laminae with a pseudo-hexagonal outline gathered in rosette-like aggregates or in starry globular groups. The compact variety of talc is called Steatite, or soapstone, used since ancient times in China to produce ornamental objects.
It is taken as a reference value for hardness, having a value of 1 on the Mohs scale. Oily to the touch, it is a bad conductor of heat. It has sometimes white, greenish-white, yellow, cream, brown, green, blue, pink luminescence. Talc plates are flexible but not elastic.
It is resistant to acids, even if concentrated, and it is infusible to the torch. Subjected to heating, at a temperature of 900 °C it completely loses its water, which it contains entirely in the hydroxyl form. It is also a powerful fat absorber.
Rich deposits of talc are found in Austria, India; Canada, the Pyrenees, South Australia and several US states.
Italian deposits of talc, whose annual production is close to 100,000 tons of mineral, are all found in northern Italy, but also in Tuscany and Sardinia.
The name "borate talc" identifies a product based on talc and boric acid.