Almandie-spessartine garnets from the alkali-feldspar Tanvald granite in northern Bohemia

Geoscience Research Reports 41, 2008 (GRR for 2007), pages 156–159

Full text (PDF, 0.9 MB)

Abstract

The two-mica alkali-feldspar granite rimming the SW periphery of the large Krkonoše-Jizera Composite Massif and known under the name Tanvald granite represents one of the most typical peraluminous granites of the Bohemian massif. Andalusite and garnet are its common accessory minerals present in almost all samples. EMPA-analyses of the garnet proved its almandine-spessartine character of the average composition centre-margin alm 0.75-0.61, spess 0.15-0.38, pyr 0.2-0.7, grosso.02-0.1. A euhedral shape of this garnet observed in thin sections was confirmed by SE immages showing well preserved 3D morphology of the icositetrahedron subordinately combined with cube.