Kutnohorite, a member of the dolomite group, is a relatively rare mineral at Mont Saint-Hilaire. It is indistinguishable from other members of the dolomite and calcite groups.
Color is usually gray, very pale green.
Luster is vitreous to pearly. Diaphaneity is transparent to translucent. Crystal Habits include sprays of prismatic crystals to 1mm and equant crystals to 0.5mm in druses. Fracture is uneven to subconchoidal. Hardness is 3.5 - 4.