porphyroidn.adj.

1794 R. Kirwan Elements Mineral. (ed. 2) I. 369 Many aggregates..cannot be arranged under any general denomination now in use. Hence I would propose to call them..Porphyroids.

1811 J. Pinkerton 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.

1885 A. Geikie 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.

1903 Geogr. Jrnl. 21 u10 (caption) Summit of High Sharpley. Cleaved porphyroid.

1940 F. F. Grout Kemp's Handbk. Rocks (ed. 6) 287 (Gloss.) Porphyroid, porphyroblastic hornfels, or schist.

1988 Philos. Trans. (Royal Soc.) A. 326 162 Also involved in the tectonics of repeated imbrication are..the epimetamorphics associated with basement porphyroids.

1798 Philos. Trans. (Royal Soc.) 88 428 Like the crystals of feldspar which we meet with in the porphyroid granites.

1852 T. Ross tr. A. von Humboldt Personal Narr. Trav. Amer. I. ii. 96 Porphyroid masses having bases of compact feldspar.

1863 J. D. Dana Man. Geol. §85. 79 These are porphyries, or porphyroid rocks.

1972 Econ. Geol. & Bull. Soc. Econ. Geologists 67 1003 (title) Inside-out hydrothermal alteration in a porphyroid Cu/Mo deposit.

1994 Museum Internat. No. 183. 27/2 This statue is of porphyroid granite with pink potassium feldspar phenocrysts, a rock commonly used in Ancient Egyptian statuary.