The Collaborative International Dictionary
Vermiculite \Ver*mic"u*lite\, n. [L. vermiculus, dim. of vermis worm.] (Min.) A group of minerals having, a micaceous structure. They are hydrous silicates, derived generally from the alteration of some kind of mica. So called because the scales, when heated, open out into wormlike forms.
Douglas Harper's Etymology Dictionary
micaceous mineral, 1814, from Latin vermiculari (from vermiculus, diminutive of vermis; see worm (n.)) + -ite. So called from its reaction when heated.
Wiktionary
n. (context mineral English) A hydrated silicate mineral which expands on heating; it is used in insulation and as a medium for planting
Wikipedia
Vermiculite is a hydrous phyllosilicate mineral. It undergoes significant expansion when heated. Exfoliation occurs when the mineral is heated sufficiently, and the effect is routinely produced in commercial furnaces. Vermiculite is formed by weathering or hydrothermal alteration of biotite or phlogopite. Large commercial vermiculite mines currently exist in Russia, South Africa, China, and Brazil.
Usage examples of "vermiculite".
David was integrated with the dirt and vermiculite, Amy took the urn over to the spigot, filling it about halfway with water.
Use either a top-grade commercial soil mixture, or combine equal parts sand, vermiculite, compost, and rich garden loam.
A more modern safe might rely on vermiculite mica or diatomaceous earth, particles of which can often be traced back from a burglary suspect's tools and clothing to the specific safe manufacturer.