Pumice (English spelling)

Japanese: 浮石 - ふせき（英語表記）pumice

A general name for volcaniclastic lava with extremely small bubbles that resemble foam. This term is usually used for light-colored lava with acidic to neutral composition, which is light and floats on water. In rhyolitic pumice, the bubbles are long and have a pearly or silky luster in the fresh walls, while in trachytic pumice, the bubbles are rough-walled and cellular. Those with alkaline composition are dark in color and dense, and are generally called scoriaceous pumice or scoria [Hill: 1774, Granger: 1931, Tyrrell: 1952]. Spuma means foam or froth, and the Latin word pumicstan means pumice. Pumice and pumice are found in Chinese classics and in Meisho from the Heian period. The origin is unknown [Utada et al.: 1978].

Source: Asakura Publishing Dictionary of Petrology Information

Japanese:

極端に小さい気胞ができてあぶくに似た火山砕屑質の熔岩の一般的な名称．通常この語は酸性から中性の組成をもつ明るい色のものに用いられ，これらは軽く水に浮かぶ．流紋岩質の浮石では気泡は長く延びて新鮮な壁では真珠状あるいは絹糸状の光沢があり，粗面岩質浮石では荒れた壁をもつ細胞状になっている．塩基性の組成をもつものは暗い色で密度も大きく，一般に岩滓質浮石（scoriaceous pumice）または岩滓（scoria）とよんでいる［Hill : 1774, Granger : 1931, Tyrrell : 1952］．spumaは泡，あぶく，ラテン語のpumicstanは軽石の意味．軽石，浮石などは中国の古典にも見られ，平安期の名抄にもある．由来は不明［歌代ほか : 1978］．

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