lonchidite

lonchidite Min.

(ˈlɒŋkɪdaɪt)

[ad. G. lonchidit, f. Gr. λογχίδιον, dim. of λόγχη spear-head (in reference to the shape of the crystals): see -ite.]

A variety of marcasite containing arsenic.

Watts Dict. Chem.