Talc

Talc itself is generally considered safe. However, it can be contaminated with asbestos fibers, which are known carcinogens that can cause serious health problems such as lung cancer and mesothelioma. It's best to wear a dust mask to avoid inhaling any dust when handling it, especially if it's in powder form.

Talc has poor toughness due to its perfect cleavage and soft internal structure, making it highly susceptible to breaking, chipping, or cracking under stress.

Talc is susceptible to water absorption, heat damage, staining difficulties, and chemical reactions. These vulnerabilities make it sensitive for daily use where such exposures are common.

Talc dominantly forms from the metamorphism of magnesian minerals such as serpentine, pyroxene, amphibole, and olivine, in the presence of carbon dioxide and water. This is known as "talc carbonation" or "steatization" and produces a suite of rocks known as talc carbonates. Talc is primarily formed by hydration and carbonation by this reaction: serpentine2 Mg3Si2O5(OH)4 + carbon dioxide3 CO2 → talcMg3Si4O10(OH)2 + magnesite3 MgCO3 + water3 H2O Talc can also be formed via a reaction between dolomite and silica, which is typical of skarnification of dolomites by silica-flooding in contact metamorphic aureoles: dolomite3 CaMg(CO3)2 + silica4 SiO2 + waterH2O → talcMg3Si4O10(OH)2 + calcite3 CaCO3 + carbon dioxide3 CO2 Talc can also be formed from magnesian chlorite and quartz in blueschist and eclogite metamorphism by the following metamorphic reaction: chlorite + quartz → kyanite + talc + water Talc is also found as a diagenetic mineral in sedimentary rocks where it can form from the transformation of metastable hydrated magnesium-clay precursors such as kerolite, sepiolite, or stevensite that can precipitate from marine and lake water in certain conditions. In this reaction, the ratio of talc and kyanite depends on aluminium content, with more aluminous rocks favoring production of kyanite. This is typically associated with high-pressure, low-temperature minerals such as phengite, garnet, and glaucophane within the lower blueschist facies. Such rocks are typically white, friable, and fibrous, and are known as whiteschist. Talc is a trioctahedral layered mineral; its structure is similar to pyrophyllite, but with magnesium in the octahedral sites of the composite layers.

Talc is a component of many products used every day. It is a common filler material used in personal hygiene products, such as baby powder, deodorant, and cosmetics. It is also used as filler for insecticides and fungicides, paper, paint, ceramics, and evening roofing materials.

The word "talc" derives from Medieval Latin talcum, which in turn originates from Arabic: طلق‎ ṭalq which, derives from Persian: تالک‎ tālk. In ancient times, the word was used for various related minerals, including talc, mica, and selenite.