Hexagonal Columnar Calcite - Black Scalenohedron Color Zoning
White hexagonal columnar calcite with black scalenohedron color zoning. It is a two generation growth calcite where the inner black scalenohedron formed first, then the white hexagonal calcite covered the black crystal. Yongchun Co., Quanzhou prefecture, Fujian, China.
The reverse (matrix) side appears to have druzy quartz covering/combined with fluorite. Under SW the quartz appears to fluoresce with about the same brightness of hardystonite, with the blue fluorescence disseminated by the overlying quartz. Under strong LW up close the fluorite is clearly visible in/near/under the quartz (see last set of pics below).
There has been a plethora of listings on Ebay and other sites highlighting this as a new find. It was apparently mined in Nov 2017, and while not a unique crystal habit for calcite, quite uncommon and exceptionally pretty under UV. Respectable under shortwave, excels under MW, and fluoresces under 365nm LW (most pics on Ebay are overexposed blobs under 390nm).
Edge-on view of a crystal showing the inner crystal
Shortwave, Longwave, and Natural (click any image)
Fluorite on the reverse matrix side, covered by druzy quartz (see each image for explanation)