Flamite (Ca,Na,K)2(Si,P)O4 (P63; a = 43.3726(18), c = 6.8270(4) Å; V = 11122.2(9) Å3), a natural analogue of the P,Na,K-doped high-temperature α-Ca2SiO4 modification, is a new mineral from Ca- and Al-rich paralava, an ultrahigh-temperature combustion metamorphic melt rock. The type locality is situated in the southern Hatrurim Basin, the Negev Desert, Israel. Flamite occurs as regular lamellar intergrowths with partially hydrated larnite, together with rock-forming gehlenite, rankinite and Ti-rich andradite, minor ferrian perovskite, magnesioferrite, hematite, and retrograde ettringite and calcium silicate hydrates. The mineral is greyish to yellowish, transparent with a vitreous lustre, non-fluorescent under ultraviolet light and shows no parting or cleavage; Mohs hardness is 5–5½; calculated density is 3.264 g cm–3. The empirical formula of holotype flamite (mean of 21 analyses) is (Ca1.82Na0.09K0.06(Mg,Fe,Sr,Ba)0.02)Σ1.99(Si0.82P0.18)Σ1.00O4. The strongest lines in the powder X-ray diffraction pattern are [d, Å (Iobs)]: 2.713(100), 2.765(44), 2.759(42), 1.762(32), 2.518(29), 2.402(23), 2.897(19), 1.967(18), 2.220(15), 1.813(15). The strongest bands in the Raman spectrum are 170, 260, 520, 538, 850, 863, 885, 952 and 1003 cm–1.

X-ray powder diffraction data for a new phase of dicalcium silicate, x-Ca2SiO4, are reported. The sample was prepared by the dehydration of hydrothermally synthesized α-type dicalcium silicate hydrate, Ca2(SiO4H)OH, at a temperature of 800 °C. Crystallographic data were Ca2SiO4, monoclinic, P21/c (No. 14), a=8.2127(5), b=9.7930(4), c=9.7954(5) Å, β=94.848(5)°, V=785.00(7) Å3, Z=8, and Dx=2.91 g·cm−3.