Llanite, Blue Quartz in Rhyolite, Texas, 1 Billion Years Old

This listing is for the Llanite slab shown. In the sun, the blue quartz spots are more bright. It is named after Llano County, Texas, the only place where it is found. Llanite is a porphyritic rhyolite with distinctive phenocrysts of blue quartz (a rare quartz color) and perthitic feldspar. Llanite comes from a rhyolite dike in the Llano Uplift of central Texas.  Radiometric dating on this llanite indicates that it is 1.106 billion years old (late Mesoproterozoic). The quartz crystals found in llanite are blue hexagonal bipyramids. The unusual blue coloration of the quartz is thought to be due to ilmenite inclusions.

Sourced From Local Collector in Shrewsbury, Massachusetts. 

LLAN-0001
Size: 4.5in x 3.2in x .5in 
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Includes card