Normandite is a brittle orange-brown sorosilicate mineral discovered in 1997 by Charles Normand (born 1963), of Montreal. It is a member of the cuspidine group and, more precisely, the Ca-Ti-dominant analogue of lavenite. Normandite occurs in Khibiny Massif, Kola, Russia; in Poudrette quarry, Mont-Saint-Hilaire, Quebec (type locality) and Tenerife, Canary Islands.
Normandite has a chemical formula of NaCa(Mn2+,Fe2+)(Ti,Nb,Zr)Si2O7(O,F)2. It crystallizes in the monoclinic-prismatic crystal system. It has a specific gravity of 3.48 to 3.5, a Mohs hardness of 5 to 6, and refractive index values of nα=1.743, nβ=1.785, and nγ=1.810. It is named after Charles Normand (born 1963), a Canadian geologist.
General Information
- Category: Mineral
- Formula: (repeating unit) NaCa(Mn2+,Fe2+)(Ti,Nb,Zr)Si2O7(O,F)2
- Crystal system: Monoclinic
- Color: Yellow, Orange brown, Orange.
Properties
It occurs as transparent to translucent orange-brown aggregates of subparallel acicular crystals up to 10 mm in length, and as patches of yellow, fibrous crystals. It has a white to very pale yellow streak and a vitreous luster. It is brittle, with distinct {100} and {001} cleavages, and a conchoidal fracture.
- Mohs scale hardness: 5 – 6
- Specific gravity: 3.48 – 3.5
- Cleavage: {100} Distinct, {001} Distinct
- Density:: 3.48 – 3.5, Average = 3.49
- Diaphaneity: Transparent to translucent
- Habit: Acicular – Occurs as needle-like crystals.
- Luminescence: Non-fluorescent.
- Luster: Vitreous – Adamantine
- Streak: pale yellowish white
Occurrences
Normandite was named for the discoverer of the mineral, Charles Normand. It is a rare mineral that occurs at the type locality at Mont Saint-Hilaire in Quebec, Canada in cavities and as vesicule fillings in nepheline syenite along with microcline, catapleiite, and eudialyte.
Additional localities include in the Khibiny and Lovozero massifs in the Kola Peninsula of Russia as large crystals in alkaline pegmatites, as well as in Spain, Morocco, Guinea, Greenland, and Brazil.
It is found in nepheline syenite and in miarolitic cavities in nepheline syenite, associated with nepheline, albite, microcline, aegirine, natrolite, catapleiite, kupletskite, eudialyte, cancrinite, villiaumite, rinkite, and donnayite-(Y).
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