Adularia

Adularia is the most common mineral in the alpine pockets besides quartz and chlorite. Today, adularia is no longer regarded as an individual mineral, but as a variety of the potassium feldspar orthoclase. Adularia is mostly white and opaque, but there are also some that are at least partially clear and sometimes have a slight moonstone sheen. Such adularia are occasionally cut into gemstones.

There are two different forms of adularia: the Maderan habit and the Fibbia habit. A peculiarity of adularia is the frequent twinning according to the Baveno and Manebach law.

Photo: Adularia with chlorite, Feldschijenstock UR, collection Felix Spahr; not for sale.