Between a Rock and a Hard Place

mineralogy

Science Snap (#35): Twinning

Charly Stamper December 18, 2014

Twinning is a phenomenon in mineralogy whereby a single crystal of a mineral has two or more parts in which the crystal lattice is differently orientated. The shared surface between two twins is called the composition or twin plane, and the orientation to either other is determined by symmetry through rotation or reflection; this relationship is described by a twin law.

Tolbachik – a mineralogist’s paradise

Charly Stamper March 17, 2014

Tolbachik is a basaltic volcanic massif lying at the southern end of the Kliuchevskoi group in Kamchatka, Russia. It comprises two overlapping cones: Plosky Tolbachik, a Holocene shield volcano extending to 3 km in diameter; and the older (Pleistocene) Ostry Tolbachik, a sharp-topped stratovolcano reaching some 3,700 m in height.