Large piece of Franklinite-Willemite ore with black submetallic Franklinite as large 1.5-2cm crystals embedded in Calite and smaller black crystals mixed with reddish-brown Willemite. With the larger Franklinite crystals in Calcite there are also several complete and partial Willemite crystals to over 2cm. Also, one one side there is a thin layer of smooth brown Kraisellite with a partial slicken side.
Before the advent of anthracite-fueled blast furnaces the Franklinite-ore was all but impossible to smelt, due to the Zn-content, and it rendered the furnaces and forges useless. In fact, a Judge in a lawsuit titled, "The New Jersey Zinc Co. VS. The Boston Franklinite Co., 1862, mentions, “This Franklinite was the most useless iron ore that had been discovered.” Later when the Iron and Zinc could be successfully separated, Franklinite produced both pig-iron and zinc oxide, proving to be more than worth the efforts needed at the furnaces. From 'Franklin & Sterling Hill, New Jersey: the world's most magnificent mineral deposits' by Pete Dunn.
