Museum Pyrrhotite is a fairly common sulfide at Mont Saint-Hilaire. The -4C polytype is monoclinic. Large crystals that appear to be pyrrhotite are usually hexagonal pseudomorphs of pyrite after pyrrhotite.
Color is usually bronze-yellow.
Luster is metallic. Diaphaneity is opaque. Crystal Habits include sharp tabular to short prismatic pseudo-hexagonal crystals to 1.5cm and as masses. Cleavage none observed. Fracture is conchoidal to uneven.