"Black" Calcite with Dolomite (ex Kay Robertson Collection)

Item Description

This piece came labeled as simply coming form "Russell County, Kansas" but I can't find a reference for any Calcite occurrences in this county. Russell County is nearly 900 square miles, and I don't know if any serious mining / quarry work has taken place in the area. The piece is certainly UNUSUAL and would make a great addition to a worldwide Calcite suite. It's labeled as "black" Calcite, and even though it's dark in reflected light, when backlit, the crystals glow with a rich golden color. On the surface, the crystals actually show slight iridescent flashes of soft green, purple and pink tones. It's possibly the Calcites have a coating of some kind of hydrocarbons / alkanes, but as we don't have another piece for reference, it's difficult to know exactly what we're dealing with here. Small curving groups of pearly white Dolomite make for a lovely accent. The largest Calcite crystals measures 1.8 cm and the largest Dolomite measures around 3 mm. Very strange material and certainly worth picking up for your Calcite collection. Ex Kay Robertson Collection (#1870). Kay is a prominent California collector, who specialized in European classics (see the article in the March-April, 2007 Mineralogical Record and the 50+ page article in the German Magazine "Mineralien Velt" November-December 2017).