Definition of rathite in US English:

rathite

noun

Mineralogy
  • Any of a group of minerals that consist of complex sulpharsenites of lead, often with thallium and other elements, and occur in crystalline dolomite in the Binnental in Valais, Switzerland; frequently with distinguishing Roman numeral; specifically (also rathite-I) the first described of these minerals, which occurs as metallic grey crystals of the monoclinic system and is distinguished from dufrénoysite by the presence of thallium, silver, and (sometimes) antimony.

Origin

Late 19th century; earliest use found in Mineralogy Magazine. From German Rathit from the name of G. vom Rath, German mineralogist + -it.