Crystals are prismatic, acicular or scaly in habit; they have a perfect cleavage parallel to the brachypinacoid (M in the figure).
Sammetblende or przibramite is a variety, from Przibram in Bohemia, consisting of delicate acicular or capillary crystals arranged in radiating groups with a velvety surface and yellow colour.
Acicular crystals, resembling rutile in appearance, ` sometimes penetrate crystals of pale-coloured amethyst, for instance, at Wolf's Island in Lake Onega in Russia: this form of the mineral has long been known as onegite, and the crystals enclosing it are cut for ornamental purposes under the name of "Cupid's darts" (fleches d'amour).
These are, according to Meyer, acicular crystals, which he calls tricizites.
It is the methyl ester of a neutral body colchicein, which may be obtained in white acicular crystals.