Alkali feldspars as a main phosphorus reservoirs in rare-metal granites: three examples from the Bohemian Massif (Czech Republic)

摘要: Phosphorus-rich alkali feldspars were found in three peraluminous highly differentiated albite-topaz-Li-mica granites the W and S parts of Bohemian Massif. The average contents P2O5 K-feldspars (Křižovy kamen 0.57 wt%, Homolka 0.77 Podlesi 0.83 wt%) are higher than albites 0.23 0.39 wt%). analyses indicate that partition coefficient phosphorus between K-feldspar albite range from 1.5 to 2.5. Measured data suggest a statistically significant difference Al3++P5+=2 Si4+ substitution mechanism for concentration. P-content Podlesi-granite represent highest natural feldspar known date (up 2.5 wt% P2O5)- It is suggested all studied retained nearly granitic melts their major reservoirs phosphorus.