Picrolite is a sepentine mineral. It is a variety of antigorite, which is a polymorph of serpentine. There are two other important polymorphs of serpentine, chrysolite, and lizardite. Serpentine, antigorite, chrysolite, lizardite, and picrolite are all hydrous magnesium iron phyllosilicate, and have the same formula, (Mg,Fe)3Si2O5(OH)4). Each polymorph has a different habit, which in the case of picrolite is platey, bordering on fibrous. It's origin is Estrie, Vancouver.