| 释义 |
ˈjasperoid, a. and n.
[f. jasper n.1 + -oid.]
A. adj. Like jasper in appearance or structure.
1876Forest & Stream 13 July 375/2 A piece of basaltic or jasperoid rock of suitable shape. 1965G. J. Williams Econ. Geol. N.Z. xii. 176/1 The lode..lies immediately alongside and to the south-east of a belt of banded jasperoid chert.
B. n. Petrol. A rock in which silica, in the form of fine-grained quartz or chalcedony, has replaced some of the original constituents (usually the carbonate of limestone).
1898J. E. Spurr in Monogr. U.S. Geol. Survey XXXI. 219 He [sc. the writer] has become impressed with the widespread occurrence of this variety of quartz, which arises from the replacement of some original rock, ordinarily limestone or dolomite, by silica from circulating waters; and there seems to be need of some term which may specifically indicate it. For this use the word ‘jasperoid’ is suggested. Jasperoid may then be defined as a rock consisting essentially of cryptocrystalline, chalcedonic, or phenocrystalline silica, which has formed by the replacement of some other material, ordinarily calcite or dolomite. 1928W. Lindgren Mineral Deposits (ed. 3) xiii. 207 Silicification of limestone, argillaceous shale and rhyolite is..a very common process taking place frequently with preservation of texture. The quartz will usually be fine-grained. Silicified limestones are called jasperoids. 1944Proc. Prehist. Soc. X. 12 The cherts and jasperoids probably came from the conglomerates at Bankrom. 1968Prof. Papers U.S. Geol. Survey No. 600-B. 112/1 Sixty-eight samples of jasperoid associated with base- and precious-metal ore deposits in 25 western mining districts..were analysed for gold. |