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Pegmatite from Vernéřov near Aš (W Bohemia) forms a steeply dipping, about 1 m stick, more than 1 km long dyke, examined to the depth more than 200 m. The pegmatite is homogeneous, without any type of zonality. The major pegmatite dyke is accompanied by a swarm of thin (up to 10 cm thick) veins. The minerals in dyke and veins originated in several episodes: (1) intrusion of granitic melt and crystalization of the main pegmatite dyke quartz+orthoclase+montebrasite, (2) origin of hydrothermal quartz-feldspar veins with common cassiterite and contemporary crystalization of cassiterite in the main pegmatite dyke, (3) crystallization of Sn-Zn-Fe-Cu-sulfides, namely stannite with admixtures of kësterite, (4) crystallization of Ag-Bi-Pb-sulfides, intenzive replacement of primary silicates with fine-grained muscovite, replacement of stannite with young cassiterite, replacement of montebrasite by hydrous Al-phosphates, (5) crystallization of strongly hydrated Al- and Fe-phosphates. The pegmatite is rich in P, Li, and Sn, but poor in F. Minerals of B or Be were not found. The only primary Li-mineral and substantial P-host is montebrasite. [ABSTRACT FROM AUTHOR]

Article presents detailed research focused on the new finds of phosphates and associated minerals from the Vysoký Kámen feldspar deposit near Krásno, Slavkovský les area, Czech Republic. It presents an erosional relict of topaz -albite granitic elevation (stock). The main granitic facies were described by various authors as aplogranites, albitites, and alkali feldspar syenites. Magmatic rocks show large scale metasomatic albitization, K-feldspatization, and locally also greisenization. Phosphate accumulations with prevailing triplite are connected to pegmatitoid, possibly greisenized veins. Triplite grains are surrounded by alteration rims of fluorapatite. Large number of phosphates (i.e., leucophosphite, perloffite, frondelite, rockbridgeite, bermanite and possibly also its Fe3+-analogue) are products of triplite alteration. They form veinlets along fissures or grains up to 100 µm, accompanied by fluorite, quartz, and possible manganese oxides. Supergene fissure mineralization with metauranocircite-I, cryptomelane, hollandite, dickite, and baryte present distinct type of mineralization, with no connection to triplite. Metauranocircite-I structure is not very stable and showed continuous transition to metauranocircite-II during the PXRD analysis. [ABSTRACT FROM AUTHOR]