vermiculite
(vəˈmɪkjʊlaɪt)
[f. L. vermicul-ārī (see vermiculate v.) + -ite1.]
1. Min. a. ‘Hydrous silicate of aluminium, iron, and magnesium, occurring in small foliated scales’ (Chester).
| 1824 T. H. Webb in Amer. Jrnl. Sci. & Arts VII. 55 If subjected to the flame of a blowpipe,..it expands and shoots out into a variety of fanciful forms, resembling most generally small worms... If this proves to be a new variety..I term it Vermiculite (worm breeder). 1862 Dana Man. Min. 149 Vermiculite..looks and feels like steatite; but when heated before the blowpipe, worm-like projections shoot out, owing to a separation of the thin leaves composing the grains. 1888 Rutley Rock-forming Min. 199 Vermiculite and Jeffreysite are considered to be altered varieties of phlogopite. |
b. pl. (See quot.)
| 1875 Ure's Dict. Arts (ed. 7) III. 1074 Vermiculites, a group of minerals resembling the chlorites, remarkable for their exfoliation before the blowpipe. |
c. Flakes of this mineral used as a moisture-holding medium for plant growth or as a protective covering for the storage of bulbs or tubers.
| 1950 Los Angeles Times Home Mag. 12 Feb. 38/3 Vermiculite is one of the finest storage materials for bulbs, tubers and corms as it insulates them from sudden temperature changes. 1981 Farmstead Mag. Winter 71/1 All that is necessary for this March project is a few water⁓proof trays, fiber or wooden slats, vermiculite for seed germination, and soilless mix such as ‘Promix’ for filling the flats. 1983 Which? Sept. 398/3 Wash off as much soil as possible, then stand the tubers, stem-down, in a dry, frost-free place..before..storing in boxes of dry peat or vermiculite. |
2. Geol. ‘A short worm-track seen on the surface of many flagstones’ (1884 Imp. Dict.).