vermiculite
Concise Oxford English Dictionary © 2008 Oxford University Press:
vermiculite /vəˈmɪkjʊlʌɪt/
▶noun a yellow or brown mineral found as an alteration product of mica and other minerals, used for thermal insulation or as a moisture-retentive medium for growing plants.
– origin C19: from L. vermiculari ‘be full of worms’ (because on expansion due to heat, it shoots out forms resembling small worms) + -ite1.
'vermiculite' also found in these Oxford entries:
