Browse Items (1651 total)

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Hand Sample: Aphanitic medium gray nephlenite. White intergrowth crystals are common throughout the sample and form long strands (approx. 0.6 - 1cm in length) on sides of sample. Sample contains some melilite.

Mostly light colored with small darker bits

Gray, less mafic than average
Representative of main rock type in quarry

Nepheline Syenite. Thin, dark vein runs through the center body of the rock.

Nepheline syenite that outcrops on west side of trail at about 9200 ft. on east side line of section.

Extremely coarse-grained muscovite schist. Large garnets visible in hand sample. Sillimanite is not recognizable in hand sample, however.

The thin section shows muscovite (with minor sillimanite) in a large band, biotite, staurolite, and…

Coarse grained sample from the Concord Granite. Thin section contains plagioclase, potassium feldspar, quartz, and muscovite. Hand sample is a coarse granite with quartz, feldspars, and muscovite.

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Hand Sample: Porphyritic latite with medium-to-coarse-grained subhedral plagioclase phenocrysts in a brown-black groundmass. Thin black veins present with green margin of contact on either side.

Limestone containing fossils of the alga, Girvanella.

Both thin section images were taken at a 400x magnification.

Mottled lithology of the Muav Limestone.

Both thin section images were taken at a 400x magnification.