Ferronigerite-2N1S Locality: Stiepelmann Mine, Arandis , Swakopmund District, Erongo Region , Namibia ( Locality at mindat.org ) Size: 2.8 x 2.3 x 1.4 cm. A superb hexagonal crystal of the rare mineral Ferronigerite. This tabular crystal has a deep reddish-brown color and a superb luster. It is .9 cm face-to-face (not even corner to corner, which would be more), which is huge for Ferronigerite. And it is very nicely colored. A great example of the species. Ex. Charlie Key. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Ferronigerite-2N1S
An iron-tin aluminium oxide-hydroxide of the nigerite group, found around sillimanite-quartz veins.
Intro adapted from Wikipedia (CC BY-SA).
Ferronigerite-2N1S is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula (Al,Fe,Zn)₂(Al,Sn)₆O₁₁(OH).
It crystallizes in the hexagonal crystal system (space group P-3m1). It is a member of the Hogbömite-Nigerite structural group.
Key properties: Mohs hardness 8–9; specific gravity 4.25–4.51; Yellow-brown streak; Vitreous luster; optically uniaxial.
IMA symbol Fng-2N1S, IMA status: approved, named in 1947.
Found in quartz-sillimanite rocks closely in association with tin-bearing granite pegmatites (Egbe district, Nigeria); in riebeckite gneiss (La Guia, Spain).
It is found associated with Quartz, sillimanite, andalusite, muscovite, garnet, cassiterite, gahnite, chrysoberyl, columbite, apatite (Egbe district, Nigeria); quartz, albite, microcline.
The name refers to Nigeria, the country where it was first found.