Fornacite

Mr Teasy-Weasy Fornacite conducts a high-end hair-styling salon in Ankh-Morpork, catering to the upper (Adora Belle Dearheart and friends) and upper-middle (Charlie's wife Henrietta) classes. This seems an unlikely occupation for a troll, but hey, it's the Big Wahoonie.

Annotation

Fornacite is a pretty yallery-greenery sort of crystalline mineral.