Leonard James Spencer, 1911 Encyclopædia Britannica, Volume 20… (1911)
“ It is found only as crystals, which belong to the hexagonal system and usually have the form of acute double pyramids terminated by the basal planes; the faces of the hexagonal pyramids are striated horizontally, and parallel to the basal plane there is a perfect cleavage. The crystals are hair-brown in colour and are translucent. The hardness is 41/2 and the specific gravity 4.36. Light which has traversed a crystal of parisite exhibits a characteristic absorption spectrum. ”
