Sepiolite

Sepiolite, also known as meerschaum (/ˈmɪərʃɔːm/ MEER-shawm, /-ʃəm/ -⁠shəm; German: (listen); meaning 'foam of the sea'), is a soft white clay mineral, often used to make tobacco pipes (known as meerschaum pipes). A complex magnesium silicate, a typical chemical formula for which is Mg4Si6O15(OH)2·6H2O, it can be present in fibrous, fine-particulate, and solid forms. Sepiolite, also known as meerschaum (/ˈmɪərʃɔːm/ MEER-shawm, /-ʃəm/ -⁠shəm; German: (listen); meaning 'foam of the sea'), is a soft white clay mineral, often used to make tobacco pipes (known as meerschaum pipes). A complex magnesium silicate, a typical chemical formula for which is Mg4Si6O15(OH)2·6H2O, it can be present in fibrous, fine-particulate, and solid forms. Originally named meerschaum by Abraham Gottlob Werner in 1788, it was named sepiolite by Ernst Friedrich Glocker in 1847 for an occurrence in Bettolino, Baldissero Canavese, Torino Province, Piedmont, Italy. The name comes from Greek sepion (σήπιον), meaning 'cuttlebone' (the porous internal shell of the cuttlefish), + lithos (λίθος), meaning stone, after a perceived resemblance of this mineral to cuttlebone. Because of its low specific gravity and its high porosity, it may float upon water, hence its German name. It is sometimes found floating on the Black Sea and rather suggestive of sea-foam, hence the German origin of the name as well as the French name for the same substance, écume de mer. In addition to its use in pipes, sepiolite is used in oil drilling and for cat litter. In construction, sepiolite can be used in lime mortars as water reservoir. Sepiolite is opaque and off-white, grey or cream color, breaking with a conchoidal or fine earthy fracture, and occasionally fibrous in texture. Due to the fact it can be readily scratched with the finger nail, its hardness is ranked at about 2 on the Mohs scale. The specific gravity varies from 0.988 to 1.279, but the porosity of the mineral may lead to error. Sepiolite is a hydrous magnesium silicate having the chemical formula Mg4Si6O15(OH)2·6H2O. When first extracted, sepiolite is soft. However, it hardens on exposure to solar heat or when dried in a warm room. Most of the sepiolite of commerce is obtained chiefly from the plain of Eskişehir in Turkey, between Istanbul and Ankara. It occurs there in irregular nodular masses, in alluvial deposits, which are extensively worked for its extraction. It is said that in this district, there are 4000 shafts leading to horizontal galleries for extraction of the sepiolite. The principal workings are at Sepetçi Ocağı and Kemikçi Ocağı, about 20 miles southeast of Eskişehir. The mineral is associated with magnesite (magnesium carbonate), the primitive source of both minerals being a serpentine. Sepiolite is also found, though less abundantly, in Greece, as at Thebes, and in the islands of Euboea and Samos. It occurs also in serpentine at Hrubschitz near Kromau in Moravia. Additionally, sepiolite is found to a limited extent at certain localities in France and Spain, and is known in Morocco. In the United States, it occurs in serpentine in Pennsylvania (as at Nottingham, Chester County) and in South Carolina and Utah. Sepiolite occurs as a secondary mineral associated with serpentine. It can occur as a precipitate in arid environments. It may be associated with dolomite and opal. Owing to its fibrous mineral nature, sepiolite veins may contain the hazardous material asbestos; however, this is true of only a very rare form of sepiolite, as the two are formed in very different environments. Even where asbestos is not present, sepiolite is often mistaken for it. Careful analytical techniques such as X-ray diffraction (XRD) are able to easily distinguish the two.