Moraskoite, Na2Mg(PO4)F, a new mineral from the Morasko IAB-MG iron meteorite (Poland)

Moraskoite, a new natural phosphate of composition Na2Mg(PO4)F, has been found in the Morasko IAB-MG iron meteorite. The new phosphate occurs in a graphite-troilite inclusion enclosed in a kamacite-taenite matrix. Associated minerals in the inclusions are chlorapatite, buchwaldite, brianite, merrillite, a new phosphate phase of composition Na4MgCa3(PO4)(4), chromite, enstatite (bronzite), kosmochlor, kosmochlor-augite, olivine, albite, orthoclase, quartz, cohenite, schreibersite, nickelphosphide, altaite, pyrrhotite, sphalerite, daubreelite, djerfischerite, whitlockite and native Cu. The inclusions are rimmed by a schreibersite-cohenite halo. Moraskoite forms aggregates up to 1.5 mm in size, with individual grains 20-300 mu m across. It is colourless and transparent, with a white streak and vitreous lustre; fluorescence is weak blue in ultraviolet radiation (254 and 360 nm); hardness is 4-5; it has irregular, conchoidal fracture and cleavage is rarely observed. Calculated density (using the empirical formula) is 2.925 g cm(-3). The moraskoite structure (Pbcn, a = 5.2117(10), b = 13.711(3), c = 11.665(2) angstrom, V = 833.6(3) angstrom(3) and Z = 8) is similar to that of its synthetic analogue. The strongest diffraction lines of the moraskoite powder diffraction pattern are as follows (d(hkl), I): 3.909(75), 3.382(52), 2.955(90), 2.606(100), 2.571(96), 2.545(68), 1.691 (67). In the Raman spectrum, the following characteristic bands are distinguished (cm(-1), strong bands bold): 1114, 1027, 962, 589, 438, 336, 308, 279, 262, 244, 193, 184, 147 and 131. The Raman data prove the absence of H2O and CO2. Moraskoite is interpreted as being a primary phosphate, which crystallized together with graphite, troilite and other accessories inside the nodule.