**Conflict of interest**

*Mineralogy - Significance and Applications*

**6. Conclusions**

following reaction:

**Acknowledgements**

component in plagioclase, during its deanorthization.

the Fürstenstein pluton is supposed by Chen and Siebel [10]. In the past, the origin of these titanite-spots granitic rocks in the Fürstenstein pluton was given in detailed discussion of older papers [6–8] and also supposed by Troll [3]. Especially according to old detailed studies of titanite-spots granodiorites and tonalites from the Fürstenstein pluton, Drescher [6], Fischer [7], and Troll [3] supposed that titanite in the light spots originated by late-magmatic and/or younger hydrothermal crystallization. In all these cases, biotite served as a source of Ti for titanite, and titanite is most likely originated from a reaction involving biotite and probably anorthite

Incorporation of the REE in titanite is realized by the coupled substitution:

Partial enrichment of REE, especially Ce and La, is significant for magmatic titanite, especially for titanite occurred in alkalic magmatic rocks and lamprophyres

Both the exchange reactions (2 and 3) are significant for primary magmatic titanite [21]. The Nb and Ta enriched titanite was described from some granitic pegmatites [31].

Titanite-rich granodiorites occur in the Austrian Mühlviertel as small irregular bodies enclosed in I/S-type granites of the Freistadt/Mauthausen suite, which are usually fine-grained and dark granitic rocks having significant large amount of

Titanite as a relative plentiful accessory mineral usually forms idiomorphic, sphenoidal grains enclosed in light "spots" of fine-grained aggregates of plagioclases and quartz. The composition of titanite ranges from 89 to 92 mol.% titanite end-member. According to its Al concentration, the analyzed titanites could be considered as low-Al titanite with an aluminum of 0.05–0.08 apfu. The Fe3+ contents range from 0.02 to 0.05 apfu. Titanite shows some Al + Fe3+ excess over F, which indicates the presence of coupled substitution of (Al + Fe3+) + (F, OH) = Ti4+ + O2<sup>−</sup>. Calculation of OH content allows the estimation of (Al + Fe3+)−OH component from 2 to 9 mol.%. The content of (Al + Fe3+)−F component is lower than the amount of (Al + Fe3+)−OH component and ranges from 0 to 8 mol.%. Titanite of these titanite-spots granodiorites together with plagioclase and quartz was originated during late-magmatic evolution. The origin of titanite can be described by the

Andesine + Ti − rich annite = Titanite + Oligoclase + Quartz (4)

Thanks are extended to the support of the Long-Term Conceptual Development Research Organization RVO 67985891 and the project of Ministry of Education, Youth and Sports (ME10083). I am also grateful to P. Gadas and R. Škoda from Institute of Masaryk University for their technical assistance by using electron microprobe analyses of selected minerals (titanite, plagioclase, biotite, amphibole).

[29, 30]. Incorporation of Nb and Ta is realized by the following reaction:

titanite spots mantled by hell aggregates of plagioclase and quartz.

Ca2+ + Ti4+ = REE3+ + (Al,Fe)3+ (2)

2Ti4+ = (Nb,Ta)5+ + (Al,Fe)3+ (3)

**48**

The author declares no conflict of interests.
