Senaite Locality: Oberaar lake area, Grimsel area, Hasli Valley, Bern , Switzerland ( Locality at mindat.org ) Size: miniature, 4.7 x 3.4 x 2.6 cm Senaite A robust 4mm crystal of this very, VERY rare lead-titanium-iron-manganese oxide. The crystal is sharp and 3-dimensional, showing all side faces. Old Siber & Siber label. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Senaite
Senaite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Pb(Mn,Y,U)(Fe,Zn)₂(Ti,Fe,Cr,V)₁₈(O,OH)₃₈.
It crystallizes in the hexagonal crystal system (space group R-3). It is a member of the Crichtonite structural group.
Key properties: Mohs hardness 6; specific gravity 5.2–5.3; Brownish black streak; Submetallic luster; optically uniaxial.
IMA symbol Sna, grandfathered status — known before the IMA’s founding, named in 1898.
Found in granite or syenite pegmatites; in a hydrothermal deposit; a detrital mineral.
It is found associated with Ilmenite, rutile, magnetite, hematite.
The mineral was named to honor Joachim Candido de Costa Sena (1852–1919), Professor of Mineralogy, School of Mines, Ouro Preto, Brazil.