GRD020ZS0
M-46
Folds
Unknown
None
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1
Ritter 154 › Cabinet 14 › Drawer P
fine-grained,folds
Carbonate-biotite-quartz-amphibole-muscovite schist with folded laminae and ptygmatic folds. Melanocratic layers: biotite, carbonate, quartz. Leucocratic layers: carbonate, biotite, trace muscovite. Medium-grained quartz veins cutting across and along laminae. Marl protolith? Original description: Q-Bi gneiss with ptygmatic folds.
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Fine-grained, amphibole-rich layer between two more coarse-grained quartz-rich layers.
2.5
plane
Fine-grained, amphibole-rich layer between two more coarse-grained quartz-rich layers.
2.5
crossed
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scan
crossed
GRD020ZT0: Ptygmatic folds. Tan/cream fine-grained layer (to the naked eye): 75% amphibole, 10% carbonate, 10% quartz, 5% biotite. Trace opaque. More coarse-grained, clear layer (to the naked eye): 50% quartz, 25% biotite, 25% calcite. Some portions of this layer are more quartz-rich. Many of the biotite crystals are aligned in all layers. (C. Eichler)
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