Calcite, Willemite, Franklinite and Zincite: A Sterling Hill, NJ Classic
This is a classic, bright fluorescent specimen from the famous Sterling mine in Sterling Hill, Ogdensburg, New Jersey. This piece contains the three primary zinc ore minerals willemite, franklinite and zincite, that put the historic Franklin/Sterling Hill zinc mines on the map. This specimen also contains abundant calcite, which back in the days of zinc mining would have been considered an undesirable gangue mineral. Under short wave UV, the willemite fluoresces bright green with phosphorescence, and the calcite shows bright orange/red fluorescence, typical for this material. The calcite also shows a phenomenon known as brief intense phosphorescence, or "BIP," meaning that for a brief moment immediately after the short wave lamp is turned off, it displays a very short-lived, but bright (intense) phosphorescent response or flash. Under long wave UV the calcite shows a dim to moderate magenta response and the willemite fluoresces dim green. The size of this classic specimen is 13.0 x 8.0 x 6.1 cm, and it weighs 761 grams.
The photographs above show fluorescence under short wave UV (upper left), phosphorescence of the willemite after short wave UV (upper right), fluorescence under long wave UV (lower left), and the specimen seen under visible light (lower right). In the visible light image, the calcite appears white, the willemite brown, the zincite orange, and the franklinite is the black mineral. Click on the above images for a larger view.
The above images show fluorescence under short wave UV (top) and red BIP (brief intense phosphorescence) or flash of the calcite after short wave UV (bottom). The duration of the BIP is < 1 sec.