Franklinite in Calcite – Sterling Mine near Ogdensburg, Franklin, New Jersey, USA
 
Metallic black, magnetic Franklinite octahedra to 4 mm on edge in cleaved grey to white Calcite matrix. Franklin is the type locality and the world's richest occurence of this zinc spinel. The manganiferous Calcite matrix shows a fire-red fluorescence in long- and short-wave UV light. Recovered on a dump in 1968, ex collection Wolfgang Stoll/Hanau. The potential for finds has been extinguished since the 1970s!