penfieldite
/ˈpɛnfiːldʌɪt/Mineralogy
noun
A rare mineral of the hexagonal system which consists of a basic lead chloride, Pb2Cl3OH, and typically occurs as tiny prisms, colourless when pure.
Origin
Late 19th century. From the name of Samuel L. Penfield, U.S. mineralogist + -ite.