Crystal data for the low-temperature form of carnegieite NaAlSiO4

The X-ray powder diffraction pattern of the low-temperature form of carnegieite (T < 943 K) has been successfully indexed by means of electron diffraction on small particles (10 μm) and subsequent least-squares refinement of 103 reflections from a high-resolution Guinier Cu Kα1 photograph. The lattice constants a = 5.0347 (6), b = 5.0822 (7), c = 16.910 (2) Å, α = 99.00 (1), β = 81.50 (1), γ = 119.09 (1)° correspond to a triclinic derivative (space group P1/P{\bar 1}) of the cubic cristobalite structure type.