Abstract
Pegmatite bodies within a granite mass at Striegau, Silesia, contain a great number of open druses, in which were deposited most of the minerals forming the basis of this study.
Five stages of mineralization are established for the Striegau pegmatites. The first, or magmatic, stage included the formation of the main quartz-feldspar pegmatite bodies, and the graphic intergrowth of quartz and orthoclase surrounding the druses. The cavities were probably formed during the second, or albitization, stage, during which albite and cleavelandite were deposited in the druses and replaced some of the orthoclase of the druse walls.
Chlorite (strigovite, prochlorite, and penninite), tourmaline, fluorite, epidote, clino-zoisite, and axinite belong to the succeeding period of druse filling. Pneumatolytic and hydrothermal action are indicated.
Zeolites, chiefly stilbite, are characteristic of the fourth stage of mineralization, which was evidently a period of cooling thermal solutions. Calcite crystals in the cavities represent the final period of mineral formation.
A table of mineral paragenesis is presented.
