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1 Acta Geologica Polonica

1 2024

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Titanite from the NYF-type pegmatites of Szklarska Poręba Huta quarry, Karkonosze granite massif, SW Poland

Mil Karolina, Gołębiowska Bożena, Pieczka Adam, Włodek Adam

Acta Geologica Polonica

2024

Vol. 74, no. 3

art. no. e20

Titanite, an accessory mineral of pegmatite related to aplogranite, was identified in the Szklarska Poręba Huta quarry within the Karkonosze granite massif in Lower Silesia, Poland. It formed during pegmatitic to hydrothermal stages. Besides the isovalent substitution Sn → Ti, the chemical composition of the mineral is characterized by three coupled substitutions: (1) (Al, Fe, Sc)3+ + (OH, F) - → Y Ti + ZO, (2) XREE3+ + Y (Al, Fe, Sc) 3+ → XCa2+ + Y Ti4+, and (3) (Al, Fe, Sc) 3+ + (Nb, Ta)5+ → 2 Y Ti. These substitutions are strongly dependent on the composition of the magma in terms of its Al2O3/TiO2 activity ratio, with the first one also influenced by the H2O/HF fugacity ratio. Fluorine, which induced the most common substitution (1), had its source in high-temperature F-bearing fluids released from rocks of the metamorphic envelope adjacent to the intruding granite. These fluids mobilized and transported various rock components (Sc, REE, Nb, Ta, etc.) among others in the form of fluoride complexes, enriching the aplogranite magma with some metallic elements. The substitution of Sn for Ti developed with decreasing temperature to the extent that in thin ore-mineralized quartz veins cutting aplogranite, titanite reaches Sn-bearing compositions up to the prevalence of Sn corresponding to malayaite.