percylite
/ˈpəːsɪlʌɪt/Mineralogy
noun
A substance originally regarded as a mineral, a hydroxychloride of lead and copper, but now thought to be a mixture of boleite and pseudoboleite.
Origin
Mid 19th century; earliest use found in Henry James Brooke (1771–1857), crystallographer. From the name of John Percy, English metallurgist who analysed it + -lite.