Browse Items (1651 total)

An example of the 3rd ring dike. This outcrop also contains dark xenoliths.

Sample contains phenocrysts of perthite. The bulk of the rock contains quartz, k-spar, and amphibole.

Contains large phenocrysts of perthite. Rocks in the outcrop also contain abundant mafic xenoliths. Sample collected from a ring dike

The bulk of the rock contains quartz, k-spar, and amphibole.

Sample from a ring dike and is fine-grained and quartz poor.

Hand Sample: Phaneritic granite with coarse-grained phenocrysts of smokey quartz and generally smaller crystals including potassium feldspar. Weathers to orange on one side and some light-gray material on the other.

Biotite and feldspar are aligned, giving the rock a texture like porphyroblastic gneiss, some feldpsar has been altered to sericite, and some larger feldspar crystals are fractured

Fedlspar and quartz exhibit fracturing

Basalt dike in gabbro with prehnite-pumpellyite overprint.

massive, tabular, sharp-edged blocks

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