Fluorite on Sphalerite, Cave-in-Rock District, Southern Illinois, Mined c. 1960's-1970's, ex. Sam and Ann Koster Collection, Large Cabinet 8.0 x 8.5 x 13.5 cm, $450. Online Dec. 19
A group of large interconnected deep brown lustrous sphalerite topped with attractive purple fluorite. Note: The fluorite is preferentially oriented over the sphalerite in classic "snow on the roof" formation. In excellent condition. A nice combination specimen of two principal ore minerals.