Euhedral crystals of complexly zoned niobian titanite (up to 0.3 mm) are enclosed in hedenbergite (Hd53—81Di15—43Jh3-5) and quartz from a hedenbergite vein skarn at Kamenne doly near Pisek, Czech Republic. They are associated with minor clinozoisite-epidote (Ps3—22), calcite, plagioclase (An95). scapolite (Me80—82), scheelite, pyrrhotite, fluorapatite, arsenopyrite, native bismuth and Bi,Te-minerals. The following textural and compositional subtypes were recognized: (I) Nb-rich titanite, (II) Nb-moderate titanite in the central zone, (III) Nb-poor, Sn-enriched titanite and (IV) Nb-poor, Al,F-rich titanite in the outer zone. The substitution Al(Nb,Ta)Ti—2 is dominant in subtypes I and II, the titanite subtype I being characterized by elevated contents of Al ≤ 0.257 atoms per formula unit (a.p.f.u.), Nb (≤ 0.161 a.p.f.u.) and Ta (≤ 0.037 a.p.f.u.). Amounts of Al, Nb and Ta in subtype II are smaller and more variable. The minor substitution SnTi—1 occurs chiefly in titanite subtype III with a content of Sn ≤ 0.039 a.p.f.u.. The substitution Al(F,OH)(TiO)_i is typical for titanite subtype IV exhibiting elevated contents of Al (s£ 0.221 a.p.f.u.), F (≤ 0.196 a.p.f.u.) and Fe (≤ 0.039 a.p.f.u.).

The negative relationship of substitutions Al(F,OH)(TiO)_i vs. SnTi—1 and Al(Nb,Ta)Ti—1 is constrained chiefly by crystal structure rather than by the composition of parent medium alone. Textural relations suggest that the Nb-moderate titanite in the core zone and entire outer zone are products of fluids-induced dissolution-reprecipitation processes. The studied niobian titanite represents a new F-enriched type from a medium-grade, calc-silicate rock.

The evolution of the trace-element patterns of quartz during crystallization of pegmatite melt was investigated using laser ablation inductively coupled plasma mass spectrometry. The contents of Al, B, Ba, Be, Cr, Fe, Ge, Li, Mn, P, Rb, Sn, Sr and Ti were analysed in quartz from the border, intermediate and core zones of four granitic pegmatites differing in degree of fractionation and origin. The material investigated originates from the pegmatite district of the Strážek Unit, Moldanubian Zone, Bohemian Massif, Czech Republic and includes: lepidolite LCT (Li-Cs-Ta) pegmatite from Rožná; berylcolumbite LCT pegmatite from Věžná; anatectic pegmatite from Znětínek; and intragranitic NYF (Nb-Y-F) pegmatite Vladislav from the Třebíč Pluton. The abundances of the elements analysed varied over wide intervals: <1 to 32 ppm Li, 0.5 to 6 ppm B, <1 to 10 ppm Ge, 1 to 10 ppm P, 10 to 450 ppm Al, 1 to 45 ppm Ti and <1 to 40 ppm Fe (average sample contents). Concentrations of Be, Rb, Sr, Sn, Ba, Cr and Mn are usually <1 ppm. Quartz from LCT pegmatites exhibits a distinct evolutionary trend with a decrease in Ti and an increase in Al, Li and Ge from the pegmatite border to the core. In comparison with the most fractionated rare-metal granites, pegmatitic quartz is relatively depleted in Al and Li, but strongly enriched in Ge. Quartz from simple anatectic and NYF pegmatites is poor in all trace elements with their evolution marked by a decrease in Ti and a small increase in Ge. There is little Al or Li and neither shows any systematic change with pegmatite evolution. Using the Ti-in-quartz thermobarometer, the outer zones of the Znětínek and Vladislav pegmatites crystallized at ∼670°C, whereas the border zone in the Rožná pegmatite yields a temperature near 610°C.