Description
Nuummite is a rare metamorphic rock composed of the amphibole minerals gedrite and anthophyllite. It is named after the area of Nuuk in Greenland, where it is found. Nuummite is usually black and opaque. It consists of two amphiboles, gedrite and anthophyllite, which form exsolution lamellae that give the rock its characteristic iridescence. Other common minerals in the rock are pyrite, pyrrhotite, and chalcopyrite, which form shimmering yellow bands in polished specimens. In Greenland, the rock formed by two successive metamorphic overburdens of an original igneous rock. The intrusion occurred in the Archean around 2800 million years ago, and the metamorphic overburden has been dated to 2700 to 2500 million years ago. The rock was first discovered in 1810 in Greenland by the mineralogist K.L. Giesecke. It was scientifically defined by O.B. Bøggild between 1905 and 1924. True nuummite is found only in Greenland. Its iridescent nature makes this rare stone sought after by gemstone dealers, collectors, and those interested in the esoteric. It is often sold with a tumbled finish.
