Microcline var. Manebach Twin with Quartz and Lepidolite, Himalaya Mine, Mesa Grande, San Diego County, California, Dr. David London Collection, Medium Cabinet 6.5 x 11.0 x 11.5 cm, $250. Online Sept. 30.
Aesthetic specimen of microcline var. Manebach twin with transparent smoky quartz and pink lepidolite. Specimen shows no point of attachment. As accounted by Dr. London "The vast majority of K-feldspars in miarolitic pegmatites are Baveno twins. Manebach twins are not rare, but uncommon. The etch patterns they develop on their surfaces are controlled by the distribution of albite lamellae in the perthitic intergrowth of the feldspar. The feldspars from the Himalaya mine are unusual because they are grey in color. That coloration is due to radiation damage from the high rubidium content of the crystals."