Sylvite, or
sylvine, is
potassium chloride (KCl) in natural
mineral form. It forms crystals in the
isometric system very similar to normal
rock salt,
halite (
NaCl). The two are, in fact, isomorphous. Sylvite is colorless to white with shades of yellow and red due to inclusions. It has a
Mohs hardness of 2.5 and a
specific gravity of 1.99. It has a refractive index of 1.4903. Sylvite has a salty taste with a distinct bitterness.