A gneiss containing both biotite and garnet as primary components. See also Garnet-biotite augen gneiss.

Gneiss is sometimes named for these minerals, examples of which include "garnet gneiss" and "biotite gneiss." Garnet Gneiss: A photograph of polished garnet gneiss from the stock of a …

Apr 23, 2023 · Mineralogy: Felsic minerals such as feldspar ( orthoclase, plagioclase) and quartz generally form the light coloured bands; mafic minerals such as biotite, pyroxene ( augite) and …

Garnet-biotite augen gneiss Darwin wrote: “Mica, quartz and feldspar (porphyritic with large crystals of do.) arranged in plane; containing garnets and joining to 467. (It is a true gneiss, a …

Biotite gneiss varies from potassium feldspar augen gneiss along the east boundary of the quadrangle to mylonite in the shear zone. The biotite gneiss has a strong, flat-lying gneissic …

Gneiss (/ n a ɪ s / nice) is a ... so geologists are careful to add descriptions of the color and mineral composition to the name of any gneiss, such as garnet-biotite paragneiss or grayish …

This garnet-rich, high-grade Lewisian rock comes from Roneval on South Harris in the Western Isles of Scotland. The rock was subjected to deep burial and temperatures exceeding 800 °C …

Slightly foliated garnet-biotite-gneiss from Passau area, showing strongly cracked almandine porphyroblasts (spotty pale-grey), in a fine-grained matrix consisting of quartz, plagioclase …

The MRV garnet-biotite gneiss is a dark, medium-grained, roughly equigranular, well-foliated gneiss that contains light-gray, coarser-grained, granular compositional banding, and is …

Mar 1, 2001 · The large garnets show four zones (AI–AIV), whereas the small garnets show three or fewer zones, indicating successive garnet nucleation with increasing nucleation densities. …