Prime examples of whiteschists include the Franciscan Metamorphic Belt of the western United States, the western European Alps especially in Italy, certain areas of the Musgrave Block, and some collisional orogens such as the Himalayas, which stretch along Pakistan, India, Nepal, and Bhutan. Talc carbonate ultramafics are typical of many areas of the Archaean cratons, notably the komatiite belts of the Yilgarn Craton in Western Australia. Talc-carbonate ultramafics are also known from the Lachlan Fold Belt, eastern Australia, from Brazil, the Guiana Shield, and from the ophiolite belts of Turkey, Oman, and the Middle East. China is the key world talc and steatite producing country with an output of about 2.2M tonnes(2016), which accounts for 30% of total global output. The other major producers are Brazil (12%), India (11%), the U.S. (9%), France (6%), Finland (4%), Italy, Russia, Canada, and Austria (2%, each).Notable economic talc occurrences include the Mount Seabrook talc mine, Western Australia, formed upon a polydeformed, layered ultramafic intrusion. The France-based Luzenac Group is the worlds largest supplier of mined talc. Its largest talc mine at Trimouns near Luzenac in southern France produces 400,000 tonnes of talc per year. Conflict mineral
Extraction in disputed areas of Nangarhar province, Afghanistan, has led the international monitoring group Global Witness to declare talc a conflict resource, as the profits are used to fund armed confrontation between the Taliban and Islamic State. Uses
Talc is used in many industries, including paper making, plastic, paint and coatings (e.g. for metal casting molds), rubber, food, electric cable, pharmaceuticals, cosmetics, and ceramics.
It can appear as a single lesion in an organ, up to a large quantity of lesions in one organ. When multiple lesions are scattered throughout an organ, it can be called a multifocal unisystem variety. When found in the lungs, it should be distinguished from Pulmonary Langerhans cell hystiocytosis—a special category of disease most commonly seen in adult smokers. When found in the skin it is called cutaneous single system Langerhans cell LCH. This version can heal without therapy in some rare cases. This primary bone involvement helps to differentiate eosinophilic granuloma from other forms of Langerhans Cell Histiocytosis (Letterer-Siwe or Hand-Schüller-Christian variant). Multifocal unisystem
Seen mostly in children, multifocal unisystem LCH is characterized by fever, bone lesions and diffuse eruptions, usually on the scalp and in the ear canals. 50% of cases involve the pituitary stalk, often leading to diabetes insipidus. The triad of diabetes insipidus, exophthalmos, and lytic bone lesions is known as the Hand-Schüller-Christian triad. Peak onset is 2–10 years of age. Multifocal multisystem
Multifocal multisystem LCH, also called Letterer-Siwe disease, is an often rapidly progressing disease in which Langerhans Cell cells proliferate in many tissues. It is mostly seen in children under age 2, and the prognosis is poor: even with aggressive chemotherapy, the five-year survival is only 50%. Pulmonary Langerhans cell histiocytosis (PLCH)
Pulmonary Langerhans cell histiocytosis (PLCH) is a unique form of LCH in that it occurs almost exclusively in cigarette smokers. It is now considered a form of smoking-related interstitial lung disease.