タルク

解説タルク,滑石ともいう．フィロケイ酸塩．ブルーサイト層{Mg(OH)2}をSiO4の四面体層ではさんだ三層構造をなす．天然には超塩基性岩の熱水変質，ケイ酸質ド.ロマイトの低温変成の生成物として産出する．単斜晶系，空間群 C 2/c，格子定数 a0 ＝ 0.528，b0 ＝ 0.915，c0 ＝ 1.89 nm．β ＝ 100°15′．塊状，葉片状，へき開{001}完全．硬度1．もろい．密度2.58～2.83 g cm－3．n1.539～1.600．複屈折率約0.05．二軸性負．光軸角2V ＝ 0°～30°．白色，淡緑色，脂感がある．膨張率が小さいため窯業原料として，その他，塗料用の充填剤，熱，電気の絶縁体として用いられる．酸に侵されない．森北出版「化学辞典（第2版）

用途紙製品?ゴム製品?セラミックス?医薬?化粧品?石けん?つや消し配合原料、品添加物 (化学工業日報社)

用途錠剤の賦型、滑沢剤、プラスチック材料の改良。

用途医薬品及び化粧品原料、添加剤、充填剤。

用途化粧品用、医薬品原料、プラスチック材料の改良。

用途ゴム薬品、医薬品原料

説明Soapstone is composed primarily of talc, and has been used for most of recorded history as a carving medium; examples thousands of years old are still extant from Egyptian, Assyrian, and Chinese cultures. The term ‘talc’ was first used in AD 869 to describe minerals that were largely composed of what we now know as talc.

天然物の起源Talc is formed under hydrothermal conditions and is a typical mineral of weaker regional metamorphism (regional dynamo-thermometamorphism). It often occurs in association with chlorite, serpentine, or magnesite. The main parent rocks that undergo metamorphic mineral reactions leading to talc formation are either ( magnesite-bearing) siliceous dolomites, or olivine- and/or pyroxene- containing ultrabasics. In ultrabasic rocks, talc is often a product of hydrothermal alteration (autometasomatism). In commercially important deposits, talc occurs in association with tremolite, calcite, quartz, and dolomite, as the product of a more intense regional metamorphism of siliceous dolomites, and with forsterite and anthophyllite due to intense regional metamorphic overprint of ultrabasics. However, talc can also be observed as an authigenic new formation, e.g., in sandy sediments and salt deposits. Other minerals that occur in association with talc include chlorites, mica, actinolite, feldspars, rutile, pyrrhotite, pyrite, magnetite, and hematite. Limonite, a product of the weathering of iron- containing minerals, especially iron- containing ore minerals, can often be found interspersed with talc.