Piece of the mineral reedmergnerite . Discovered in Dara-i-Pioz, Tajikistan. Exhibit of the "Earth and Man" Museum in Sofia, Bulgaria. — Photo: Vassia Atanassova - Spiritia · CC BY-SA 3.0
Reedmergnerite
A sodium borosilicate — the boron analogue of albite — named for Frank Reed and John Mergner.
Intro adapted from Wikipedia (CC BY-SA).
Reedmergnerite is an IMA-recognized mineral species in the silicate class, with the chemical formula NaBSi₃O₈.
It crystallizes in the triclinic crystal system (space group C-1). It is a member of the Feldspar structural group.
Key properties: Mohs hardness 6–7; specific gravity 2.7–2.78; Vitreous luster; optically biaxial.
IMA symbol Rm, IMA status: approved, named in 1955.
Occurs as authigenic crystals along bedding laminations, in brown dolomitic rock and black oil shale from well cuttings (Duchesne Co., Utah, USA); in highly evolved pegmatite in an alkalic massif (Dara-i-Pioz massif, Tajikistan).
It is found associated with Eitelite, shortite, nahcolite, searlesite, leucosphenite, aegirine, analcime, magnesio- riebeckite (Duchesne Co., Utah, USA); leucosphenite, eudialyte.
The mineral was named to honor Frank S. Reed (1894-?) and John L. Mergner (1894-?), petrographic technicians with the U.S. Geological Survey.