ABSTRACT

     Nalipoite, the natural analogue of NaLi₂PO₄, occurs as anhedral to subhedral blocky grains up to 2 mm in sodalite or analcime and as irregular grains (0.2 mm) in cavities in sodalite syenite xenoliths in the nepheline syenite, Poudrette quarry, Mont Saint-Hilaire, Quebec.  It is associated with sodalite, analcime, clinoamphibole, aegirine, cancrinite, serandite, lovozerite, villiaumite, ussingite, steenstrupine-(Ce), eudialyte, thermonatrite, natrophosphate, sidorenkite, rasvumite, revdite, vuonnemeite, vitusite-(Ce), chkalovite, terskite, silinaite, lintisite and others, including many unidentified minerals.  The mineral is white, very pale blue or yellow with a white streak, vitreous, transparent to translucent.  The mineral is brittle with a Mohs hardness about 4, and nonfluorescent in ultraviolet light.  Cleavages {100}, {010}, {001}and {110} are good, with another distinct direction, possibly {101}; fracture uneven; D (meas.) 2.58 (1), D (calc.) 2.612 g/cm³.  The mineral dissolves readily in 1:1 HNO₃, less readily in 1:1 HCl and slowly in H₂SO₄.  Nalipoite is biaxial (-),
a 1.533 (1), b 1.540 (1), g 1.541 (1), 2V (meas.) = 49 (1)° and 2V (calc.) = 41° (l 589 nm).  Orientation:  X = a, Y = c, Z = b.  The mineral is orthorhombic, Pmnb, a 6.884 (2), b 9.976 (4), c 4.927 (2) Å.  The strongest eight X-ray diffraction lines [d in Å (I)(hkl)] are: 

     The chemical formula was confirmed by a crystal-structure analysis.  Electron- microprobe analyses gave (average):

© 1991  The Canadian Mineralogist