| 释义 |
▪ I. schist1 Geol.|ʃɪst|
Also 8 shist; and see schistus.
[a. F. schiste (in 16th c. scisth, in 18th c. occas. chite, in accordance with the then usual pronunciation), a. L. schistos adj., fissile, readily splitting (lapis schistos, a kind of stone mentioned by Pliny), a. Gr. σχιστός (σχ. λίθος, ‘probably talc’, L. & Sc.), f. σχιδ-, σχίζειν to split: see schism n.]
A crystalline rock whose component minerals are arranged in a more or less parallel manner.
Some continental writers call any fissile rock a ‘schist’, prefixing the word ‘crystalline’ to denote the rocks described in the above definition. The parallel structure in schists is independent of original stratification, being due to metamorphic action; indeed, many schists are modified igneous rocks.
1795Mills in Phil. Trans. LXXXVI. 41 A thin stratum of vegetable soil lies uppermost; then clay, mingled with fine sand, composed of small particles of quartz, mica, and shist. 1832H. T. De la Beche Geol. Man. (ed. 2) 309 The schist, and its accompanying clays, contain an abundance of fossils. 1885Teall (title of paper) On the Metamorphosis of Dolomite into Hornblende-Schist. 1886Bonney Pres. Addr. Geol. Soc. 57 Again in the mouth of one geologist a ‘schist’ will mean any rock that has a rough fissility,..while another restricts the term to the foliated rocks. 1903A. Geikie Text-bk. Geol. 246 A rock possessing a crystalline arrangement into separate folia is in English termed a Schist. 1904Van Hise Treat. Metamorphism (U.S. Geol. Survey) 780 Illustrations of the use of the term Schist both as the name of a definite rock and with a structural signification are furnished by the terms mica-schist, chlorite-schist, and hornblende-schist as generally used.
b. attrib.
1839Ure Dict. Arts 36 The evaporation of the Schist Lixivium. Ibid. 39 For evaporating the schist liquors. 1878Schiller's Technol. Dict., Schist-oil. 1903Geikie Text-bk. Geol. iv. viii. §1 (ed. 4) 782 The schist district of the Elbe valley hills in Saxony.
▪ II. schist2 Acoustics. rare.|skɪst|
In quot. skhist.
[ad. Gr. σχιστόν, neut. of σχιστός divided: see schist1.]
A small interval equal to one-eighth of a schisma.
1875[see schistic a.3]. |