Kutnahorite
0.74 ct
Florescent
Trillion Cut
6.30 x 6.10 x 3.20 mm
N.J. USA
max 6235

Kutnahorite

is a calcium manganese carbonate mineral with formula Ca(Mn,Mg,Fe++)(CO3)2 and hardness of 3.5-4.

Here is associate with black franklinite and pink willemite that fluoresce in green.

It comes from Sterling Hill Mine, Ogdensburg, NJ, USA.