K-Feldspar var. Adularia

A rather spectacular, gemmy to translucent twinned crystal group of Adularia, a gemmy variety of potassium Feldspar (K-Feldspar), from the Maderanertal area in Uri, Switzerland. Well-developed, wedge-like crystals of Adularia are stacked upon each other in an interpenetrant twinned habit, individual crystals measuring to 5.7 cm. The latter, the largest crystal, forms the base of this large miniature, with all other crystals stacked on top. The edges of the Adularia crystals are accented by narrow, light sage green inclusions of Chlorite. This finely disseminated Chloritic dusting is also deposited preferentially along, and following, the many distinct striations on the crystal faces, producing most attractive linear patterns.