perlite Min.
(ˈpɜːlaɪt)
Also pearlite.
[= F. perlite, G. perlit, mod. f. F. and Ger. perle pearl: see -ite2.]
A peculiar form of obsidian and other vitreous rocks, in which the mass sometimes assumes the form of enamel-like globules; pearlstone; spec. fine or coarse grains of this mineral used, with appropriate nutrient solutions, as a medium for the growth of plants.
| 1833 Lyell Princ. Geol. III. 222 Resinous silex.., pearlite, obsidian, and pitchstone abound. 1879 Rutley Study Rocks xi. 193 Perlite must be regarded as the vitreous condition of the felsitic rhyolites. 1882 Geikie Text-bk. Geol. ii. ii. vi. 141 Perlite (Pearlstone) another vitreous condition of sanidine lava..of vitreous or enamel-like globules. 1956 T. M. Morrison in N.Z. Jrnl. Agric. XCIII. 503/1 The coarse grade of expanded perlite now on the market in New Zealand is ideal for plant growth. Ibid. 503/3 Perlite is cheap enough to be thrown out after several crops have been raised in it. 1971 ‘D. Halliday’ Dolly & Doctor Bird viii. 106 We saw the trucks going by from the big netted nursery... Trucks full of potted plants, and bags of horticultural perlite, and Canadian sphagnum peat moss. 1976 A. C. Bunt Mod. Potting Composts ii. 38 Perlite is an alumino-silicate of volcanic origin and is widely used in the USA and New Zealand, both countries having large natural deposits of this mineral. |
Hence perˈlitic a., of or pertaining to perlite.
| 1879 Rutley Study Rocks xi. 183 Showing that the perlitic structure had no existence when the rock was in a state of fluxion. 1881 Judd Volcanoes 110. |