Jarosite , Natrojarosite Locality: Centennial Eureka Mine (Blue Rock), Tintic District, East Tintic Mts, Juab County , Utah , USA ( Locality at mindat.org ) Size: small cabinet, 9.4 x 6.2 x 2.5 cm Jarosite & Natrojarosite (Utahite) "Utahite" came from only a small find in Utah, and this is a very old specimen from the type locality, featuring minute blue microcrystals on matrix with malachite, barite, and gods know what else - probably a whole schmear of microcrystallized rare copper minerals here! To confuse matters more, the name was discredited and this material was then shown to be jarosite/natrojarosite; and a NEW species named Utahite was then christened afterwards. This old "utahite" was a combination of jarosite or natrojarosite (this is way too old to be the newer species utahite). I don't know what the hell all this copper-rich stuff is, but it is really interesting as a historic specimen and from a great locality, and worth further study to somebody with the resources to pursue analysis. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Natrojarosite
The sodium analogue of jarosite — a basic hydrous sodium-iron sulfate of the oxidized zone.
Intro adapted from Wikipedia (CC BY-SA).
Natrojarosite is an IMA-recognized mineral species in the sulfate class, with the chemical formula NaFe³⁺₃(SO₄)₂(OH)₆.
It crystallizes in the hexagonal crystal system (space group R-3m). It is a member of the Alunite-Alunite structural group.
Key properties: Mohs hardness 3; specific gravity 3.11–3.18; Vitreous luster; optically uniaxial.
IMA symbol Njrs, IMA status: approved, named in 1902.
Formed typically in the oxidized zone of mineral deposits by alteration of pyrite in the presence of sodium; rarely as a volcanic sublimate.
It is found associated with Gypsum, alunite, jarosite, plumbojarosite.
As the sodium, natrium, analog of jarosite.