ABSTRACT
The Upper Carboniferous porphyritic microgranite of Altenberg-Frauenstein forms a 36 km long and up to 18 km wide complex of ring dykes of the Teplice-Altenberg caldera in the German-Czech border region of the Eastern Erzgebirge/Krušné Hory. According to the definition of rapakivi granites after Haapala and Rämö (1992) the porphyritic microgranite of Altenberg-Frauenstein containing plagioclase mantled K-feldspar may be considered as rapakivi granite. But due to its Carboniferous age and being the only known occurrence of a granite with rapakivi texture in the German part of the Variscan belt, the microgranite of Altenberg-Frauenstein hold an exceptional position.
