| 释义 |
porphyroid, n. (a.) Geol. and Min.|ˈpɔːfɪrɔɪd|
[f. porphyro- + -oid. So F. porphyroïde.]
A. n. A rock resembling porphyry or of porphyritic structure.
1796Kirwan Elem. Min. (ed. 2) I. 369 Many aggregates..cannot be arranged under any general denomination now in use. Hence I would propose to call them..Porphyroids. 1811Pinkerton Petralogy I. 88 Porphyroid. This denomination includes such substances as approach the porphyritic structure. In a strict derivation of the term porphyry,..the black and green kinds could only be termed porphyroids. Ibid. 211 Granitic porphyroids are so abundant in all primitive mountains, that it is scarcely necessary to select examples. 1885Geikie Text-bk. Geol. 131 Porphyroid occurs among the schistose rocks of Saxony, in the palæozic area of the Ardennes, as well as in Westphalia and other parts of Europe.
B. adj. Resembling or akin to porphyry.
1798Greville in Phil. Trans. LXXXVIII. 428 Like the crystals of feldspar which we meet with in the porphyroid granites. 1852Th. Ross Humboldt's Trav. I. ii. 96 Porphyroid masses having bases of compact feldspar. 1862Dana Man. Geol. §85. 79 These are porphyries, or porphyroid rocks. |