Siderite var. Sphaerosiderite w/ Opal (rare combo) Robertson Coll.

Item Description

Multi-hued, nubby spherical aggregates of moderately translucent siderite variety sphaerosiderite rhombs richly fill a sculptural vug in basalt matrix. The vein of glassy colorless opal is a super accessory. Ex Kay Robertson Collection # 8140 and acquired from the Cisneros' in the Spring of 1977. It was previously in a German collection. 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 Welt" November-December 2017). Rare, excellent, colorful and showy, undoubtedly older combination material from the extinct basalt quarries here. This is not smithsonite, as the Kay label indicates.