Normandite is an orange-brown, monoclinic sorosilicate mineral with the idealised formula . It is the titanium analogue of låvenite and a member of the wöhlerite group.
History Charles Normand discovered the mineral in 1980 at the Poudrette quarry, Mont-Saint-Hilaire, Quebec. George Y. Chao and Robert A. Gault described it as a new mineral species in 1997 and named it in Normand's honour.
Occurrence and properties The Poudrette quarry is the type locality. There, normandite occurs in nepheline syenite and its miarolitic cavities, associated with nepheline, albite, microcline, aegirine, natrolite, catapleiite, kupletskite, eudialyte, cancrinite, villiaumite, rinkite and donnayite-(Y). It forms transparent to translucent orange-brown aggregates of subparallel acicular crystals up to long, as well as yellow fibrous patches.
The mineral has a white to very pale-yellow streak, a vitreous lustre, distinct {100} and {001} cleavages, and a conchoidal fracture. Its Mohs hardness is 5–6 and its measured density is about 3.50 g/cm3.
Classification and structure Normandite crystallises in space group P21/a. Its structure has the four-column-wide walls of cation-centred polyhedra characteristic of wöhlerite-group minerals, interconnected by corner sharing and by Si2O7 groups. Its relationship to låvenite principally reflects substitution of Ti for Zr in corresponding structural sites.
References
Webmineral data Mindat with location data Saint-Hilaire The Canadian Mineralogist 1999 abstract