pyrolusite (n.) Look up pyrolusite at Dictionary.com
"manganese dioxide," 1828, the name given in Roman times, when it was used, in a heated state, to de-colorize glass, from Greek elements pyro- "by heat, by fire" (from PIE root *paewr- "fire") + lysis "a loosening" (from PIE root *leu- "to loosen, divide, cut apart").