The Collaborative International Dictionary of English v.0.48:

Haematoin \H[ae]*mat"o*in\ (h[-e]*m[a^]t"[-o]*[i^]n), n.
   [H[ae]mato- + -in.] (Physiol. Chem.)
   A substance formed from the hematin of blood, by removal of
   the iron through the action of concentrated sulphuric acid.
   Two like bodies, called respectively h[ae]matoporphyrin and
   h[ae]matolin, are formed in a similar manner.
   [1913 Webster]