| 释义 |
protogine Geol.|ˈprəʊtədʒɪn|
[a. F. protogine (1806, Jurine, Journ. des Mines, Paris, XIX. 372), irreg. f. Gr. πρῶτο-ς first + γίν-εσθαι to be born or produced (intended to express ‘first-produced’, the rock being assumed to be the most ancient of all).]
A variety of granite occurring in the Alps, in which chlorite often takes the place of biotite (secondary white micas being sometimes developed), and in which a foliated structure has frequently been produced by dynamic action.
It was for a long time erroneously supposed to contain talc, and called talcose granite; its foliated structure also led to its being classed as a variety of gneiss. It abounds esp. in the chain of Mont Blanc, of which mountain it forms the summit.
1832H. T. De la Beche Geol. Man. (ed. 2) 37 Crystalline compounds, arranged in strata, such as saccharine marble,..gneiss, protogine, &c. 1849Dana Geol. xiii. (1850) 564 Some of the veins in this Mellaca Hill consist of protogine, or a grayish-white granular compound of feldspar and compact talc. 1869Bristow tr. Figuier's World Bef. Deluge ii. 35 Protogine is a talcose granite, composed of felspar, quartz, and talc or chlorite, or decomposed mica. 1879Rutley Stud. Rocks xii. 212 Protogine is a gneiss in which, in addition to the ordinary constituents of granite, a greenish, pearly, or silvery, talcose mineral is present. |