Unusual massive brown nonfluorescent sphalerite. Most sphalerite from the Franklin – Sterling Hill area is iron-poor and colorless to very pale honey-brown, the variety called “cleiophane” by collectors. Dark brown, massive sphalerite, abundantly present by the ton at hundreds of other localities, is uncommon in the Franklin and Sterling Hill deposits. Most, if not all, postdates formation of the orebodies and is a product of later mineralization events.