20038 Calcite, Pyrite, Marcasite, Conco Mine, North Aurora, Kane Co., Illinois, USA

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 City Center (aka Innsuites), and a close up of my specimen’s big brother!