noun
vermiculite
A hydrous phyllosilicate mineral used in horticulture, construction, and insulation. Technical term; common in gardening and industrial contexts.
園芸用の蛭石は、土に混ぜて使います。
Horticultural vermiculite is used by mixing it into soil.
蛭石は断熱材としても利用される。
Vermiculite is also used as a thermal insulation material.
The Japanese name 蛭石 (hiru-ishi) literally means 'leech stone', likely from the way the mineral expands and wriggles when heated, resembling a leech. The English name 'vermiculite' comes from Latin 'vermiculus' (little worm) for the same reason.