A geochemically primitive, moderately fractionated, LCT pegmatite from Lutomia (Góry Sowie Block, SW Poland) has been characterized in respect of the primary and secondary phosphate assemblages. The pegmatite crystallized from anatectic granitic magmas mobilized by M 2-3 metamorphism at ~370-380 Ma. Three phosphate assemblages had a different origin: (1) the primary, magmatic one [graftonite-(I)-beusite-(I) + triphylite ± sarcopside], (2) a secondary, metasomatic one [Ca-rich graftonite-(II) -Ca-rich beusite-(II) + wolfeite/triploidite/stanĕkite + hagendorfite/alluaudite + kryzhanovskite ± a Ca-bearing phosphate close to ferromerrillite + fluorapatite], and (3) a secondary, hydrothermal and weathering one [ferrisicklerite ± heterosite + phosphoferrite-kryzhanovskite + ludlamite + vivianite ± hureaulite + earlshannonite-whitmoreite + strunzite-ferrostrunzite + beraunite + dufrénite + jahnsite-(CaMnFe), -(CaMnMn) and -(MnMnMn) + landesite + fairfieldite + Mn 2+ -bearing hydroxyapatite]. The magmatic assemblage resulted from the breakdown of a primary, high-T, Ca-and Li-enriched graftonite-like phase. It was induced by cooling and elevated incompatible Ca, Na, Li and F concentrations. The metasomatic assemblage reflects the destabilization of the magmatic phosphates and their Ca-and Na-metasomatism by a high-T fluid connected with a PO 4 -bearing melt, which previously had evolved along with graftonite-(I)-beusite-(I). The assemblage of secondary, hydrothermal and weathering, phosphates was a result of lower T alteration by hydrothermal fluids and meteoric water by both topotactic Fe and Mn oxidation as well gradual hydration and Fe oxidation. Taken together, the Lutomia pegmatite has been compared to the phosphate-bearing pegmatite at Michałkowa and the mixed NYF + LCT, PO 4 -poor pegmatitic system of Piława Górna.Keywords: phosphate-bearing pegmatite, LCT anatectic pegmatite, Lutomia, Poland Received: 16 October 2013; accepted: 25 November 2014; handling editor: Milan Novák The online version of this article (doi: 10.3190/jgeosci.185) contains supplementary electronic material.Moreover, Łodziński and Sitarz (2009) studied graftonite and sarcopside from Michałkowa.The aim of this paper is a description of the Lutomia pegmatite, as the currently best representative of phosphate pegmatitic mineralization in the GSB, and an evaluation of its relationships to the other important pegmatites in the unit. Particular attention is being paid to textural relations and chemical compositions of the minerals that reflect the geochemical evolution of the pegmatiteforming melts.
Maneckiite, ideally NaCa2Fe22þ (Fe3+Mg)Mn2(PO4)6(H2O)2, was found in a pegmatite at Michałkowa, Góry Sowie Block, SW Poland. The mineral forms subhedral and anhedral crystals ~150 μm × 150 μm in the outer zone of phosphate nodules, where it is associated with fluorapatite, wolfeite, Ca-rich graftonite and alluaudite-group minerals. Maneckiite is transparent, dark brown, with a colourless streak and vitreous lustre, brittle, and has a good cleavage // {010}, a splintery fracture and a Mohs hardness of ~5. The calculated density is 3.531 g cm–3. Maneckiite is pleochroic: α = dark green, β = dark blue/green, γ = light brown/tan, biaxial (+) with refractive indices α = 1.698(2), β = 1.706(2), γ = 1.727(2) and birefringence Δ = ~0.03; 2Vmeas. = 65.9 (1.5)° and 2Vcalc. = 64°, dispersion is obscured by the dark colour, and optical orientation X//a, Y//b, Z//c. Maneckite is orthorhombic (Pcab) and has unit-cell parameters a = 12.526(4) Å, b = 12.914(5) Å, c = 11.664(4) Å and V = 1886.8(5) Å3. The strongest reflections are (dhkl in Å; I; hkl): 2.759, 100, 402; 2.916, 78, 004; 3.020, 68, 401; 2.844, 35, 014; 2.869, 31, 240; 2.825, 30, 042. Maneckiite has the wicksite structure and is its M(3)Mn-analogue. The mineral crystallized as a product of Na- and Ca-metasomatism induced by a HT fluid in the presence of Al3+ from a neighbouring aluminosilicate melt. A Gladstone-Dale index, 0.027, places maneckiite in the category ‘excellent’.
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