Rhyolite ("Picture Rock") (ex Willard Wulff Collection)

Item Description

Rhyolite is not a mineral species, but is an igneous rock containing Quartz, Sanidine Feldpsar and Plagioclase Feldspar along with minor Mica (typically Biotite) and Amphiboles like Ferro-Hornblende. It is the extrusive equivalent to granite. This is a slice of polished Rhyolite from Mexico which has been given the name "Picture Rock". Swirling patterns of sandy, beige, and silvery hues make for a gorgeous appearance. A slight amount of dendritic growth and grains of sand seem to be frozen inside. The piece comes from the collection of Willard W. Wulff (1904-1998) of Colorado Springs, Colorado, a prominent figure and collector of Colorado minerals. Wulff was one of the founding members of the Colorado Springs Mineralogical Society in 1936. You can read Willard's bio on the Mineralogical Record website here ( http://www.minrec.org/labels.asp?colid=1528 ). The piece comes with a typed 3x5 index card label from Wulff that states the piece was acquired from Tony Amshoff of Kino Rocks and Minerals in Tucson, Arizona. The label also says the piece is repaired. A wonderfully historic and eye-catching specimen of this well known material from this classic locality.