Browse Items (1651 total)

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massive, tabular, sharp-edged blocks

Basalt dike in gabbro with prehnite-pumpellyite overprint.

Fedlspar and quartz exhibit fracturing

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

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.

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

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.

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 orthoclase, ligoclase, and quartz phenocrysts and has alterations of kaolinite, sericite, and epidote

Quartz and feldspar phenocrysts, rounded diabase inclusions

Fenitized porphyroblastic Gneiss.

Hand Sample:

Entirely coarse-grained rock except for 2 cm wide dark fine grained band. Obvious traces of oxidation appear on all sides, dominating the most weathered sides of the rock.

Macroscopic: Mega-porphyroblastic andalusite, cordierite, staurolite, biotite, garnet schist. Relict bedding, cross bedding or graded bedding may be apparent in some samples. Mineral zone: staurolite-andalusite. Microscopic: Large garnet phenocrysts…

The porphyroblastic metasediments/hybrid rocks were interpreted by Eales and his co-workers to be metamorphosed "Red Beds" Formation sediments but could be magmatic in origin. The samples illustrate the range in textures; see KBR 13 and KBR 14 to…

The porphyroblastic metasediments/hybrid rocks were interpreted by Eales and his co-workers to be metamorphosed "Red Beds" Formation sediments but could be magmatic in origin. The samples illustrate the range in textures; see KBR 12 and KBR 14 to…

The porphyroblastic metasediments/hybrid rocks were interpreted by Eales and his co-workers to be metamorphosed "Red Beds" Formation sediments but could be magmatic in origin. The samples illustrate the range in textures; see KBR 12 and KBR 13 to…

Macroscopic: Porphyroblastic staurolite, andalusite, cordierite, garnet, biotite, chlorite, muscovite schist. Cross bedding or graded bedding may be apparent in some samples. Mineral zone: staurolite-andalusite. Microscopic: Large garnet phenocrysts…

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