sylvite
noun
syl·vite ˈsil-ˌvīt 
variants or less commonly sylvine
ˈsil-ˌvēn
: a mineral that is a natural potassium chloride and occurs in colorless cubes or crystalline masses
Word History
Etymology
alteration of sylvine, from French, from New Latin sal digestivus Sylvii digestive salt of Sylvius, from Sylvius latinized name of Jacques Dubois †1555 French physician
First Known Use
1868, in the meaning defined above