Microcline, a potassium aluminum silicate mineral of the feldspar group, was first verified from Franklin by Kemp (1893a) and is surely the "green feldspar" reported by Nuttall (1822). Some material has been called amazonstone or amazonite.

Where is Microcline found?

Microcline is found at Baveno, Italy; Kragerø, Nor.; Madagascar; and, as amazonstone, in the Urals, Russia, and Florissant, Colo., U.S. For detailed physical properties, see feldspar (table). Microcline is the form of potassium feldspar that is stable at the lowest temperatures.

How is Microcline formed?

Microcline (KAlSi3O8) is the triclinic low-temperature K–feldspar stable at temperatures lower than 500°C. It is usually formed by recrystallization from feldspar, and sometimes by direct crystallization from magma and hydrothermal processes.