MetaAnkoleite

specimen number:
2133342

location:
Sterling Mine, Ogdensburg, New Jersey, USA

description:
Yellow micro crystals and masses of this rare mineral across the top of a massive franklinite and willemite matrix.

The Sterling Hill mine, located in Ogdensburg, Sussex County, New Jersey, is a world-famous underground zinc deposit that operated for more than a century. Geologically, the ore body is hosted within the Precambrian Franklin Marble and forms a massive, complexly folded, stratiform synclinal structure. Unlike most global zinc deposits dominated by iron sulfides, Sterling Hill features a unique geochemical assemblage characterized by an absence of sulfides and a wealth of rare zinc-manganese oxide and silicate minerals, primarily franklinite, willemite, and zincite. Organized underground mining began in the mid-19th century and expanded substantially under the consolidation of the New Jersey Zinc Company in 1897. The mine experienced continuous, highly mechanized deep-shaft extraction until economic factors and declining ore reserves led to the permanent cessation of all commercial production in March 1986. Today, the site operates as a celebrated museum and educational foundation, preserving the historical tunnels and remaining renowned among collectors for producing more than 350 distinct mineral species, many of which exhibit brilliant fluorescence.

Meta-ankoleite is an exceptionally rare secondary potassium uranium phosphate mineral belonging to the meta-autunite group. Geologically, it forms under highly oxidizing conditions on vein surfaces within uranium-bearing rock or as a late-stage alteration product in complex mineral environments. The mineral crystallizes in the tetragonal system, typically appearing as minute clusters of tabular, mica-like plates or scaly aggregates that exhibit a distinct, pale yellow to yellowish-green color. In terms of its physical properties, it displays perfect cleavage along one plane, transparent to translucent diaphaneity, and a relatively low Mohs hardness of 2 to 2.5. Like many related uranyl phosphates, meta-ankoleite contains uranium, making it strongly radioactive. A notable feature of this species is its intense response to ultraviolet light, under which it fluoresces a brilliant neon green color under shortwave UV radiation.

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