The Collaborative International Dictionary of English v.0.48:

Cerusite \Ce"ru*site\, Cerussite \Ce"rus*site\, n. (Min.)
   Native lead carbonate; a mineral occurring in colorless,
   white, or yellowish transparent crystals, with an adamantine,
   also massive and compact.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cerussite
    n 1: a mineral consisting of lead carbonate that is an important
         source of lead [syn: cerussite, white lead ore]