Calcozincite- A Bright Rainbow of Colors from Sterling Hill, New Jersey

This brightly fluorescent specimen of calcozincite was collected during a 2019 night dig at Sterling Hill, New Jersey. Calcozincite is a rock composed of zincite, calcite, willemite, hydrozincite and fibrous minerals such as tremolite, and is found in association with slickensides along fault fractures. Under short wave UV, this specimen shows a bright rainbow of fluorescent colors. Bright green willemite and red calcite dominate the fluorescent response, with blue fluorescent accents provided by patches of hydrozincite. The size of this specimen is 92 x 41 x 15 mm, and it weighs 85 grams.

Due to the asbestiform nature of this material, caution should be used when handling to prevent inhalation of the fibers.

Chalcozincite from Sterling Hill, New Jersey showing bright fluorescence under short wave UV (254 nm). Willemite fluoresces green, calcite red/orange, and hydrozincite shows a blue response.

Phosphorescent response following exposure to short wave UV. Although the red afterglow of the calcite and the blue of the hydrozincite are short-lived (<2 sec.), the bright green phosphorescence of the willemite persists for 30-60 seconds.

Same calcozincite specimen shown under visible light. This is a light colored, fibrous, asbestiform rock with some black franklinite crystals and red/orange areas of zincite. Brightly fluorescent under short wave UV (see above photographs).

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