Platy cleavages and acicular crystals of the very rare selenium mineral nordstromite from the type locality (Falun, Dalarna, Sweden), associated to chalcopyrite. — Photo: David Hospital · CC BY-SA 4.0
Nordströmite
Nordströmite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula Pb₃CuBi₇(S,Se)₁₄.
It crystallizes in the monoclinic crystal system (space group P2_1/m).
Key properties: Mohs hardness 2–2.5; specific gravity 7.12.
IMA symbol Nsm, IMA status: approved, named in 1978.
Hydrothermal in origin.
It is found associated with Wittite, friedrichite, bismuthinite (Falun, Sweden); gold, chalcopyrite, neyite, quartz (Johnny Lyon Hills, Arizona, USA).
The mineral was named to honor T. Nordström (1843–1920), Swedish mining engineer who first studied the sulfosalts from Falun.