Purple cubes with small modified edges with tiny brassy marcasite crystals. Some of the matrix is vein calcite that fluoresces bright red. Width of view 9mm. Stack of 130 images.
Pyrite after marcasite, with calcite and a second generation of pyrite. The calcite is fluorescent pink under longwave UV. Video best viewed full screen.
Inclusions of pyrite and marcasite. From the Wise Lake Formation. Ex Jared Freiburg, Saga Minerals. Acquired at Tucson in 2011. And here is Jared with one of his cases in 2011 at the Hotel Tucson...
ex Bernie and Margaret Day Collection
JL0650. Frank Robinson
More likely pyrite