Subconchoidal, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references
Sectile Curved shavings or scrapings produced by a knife blade, (e.g. graphite).
Octahedral, perfect on {111}, parting on {011}
Perfect on {010}; poor on {100} and { 1 02}.