Browse Items (1651 total)

intrusive

Plagioclase altered to epidote and flaky sericite, rock has undergone slight metamorphism

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Rock Sample:
The sample color has a cream colored matrix with dark green phenocrysts. The sample contains Laumontite, which is a mineral in the zeolite group. There is a white talc-like substance on upper part of sample. Phenocrysts are medium to…

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Rock Sample:
The color of the crystals within the sample is half-white and half-black in color. The internal part of the sample feels rough, but the outside layer of the sample feels more like a fine-grained. This could be due to erosion on the…

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Rock Sample:
The samples color has a white matrix with dark green phenocrysts. It is phaneritic. There is evidence of chemical weathering due to the presence of a dark brownish orange film on the sample--may be oxidation. There is a sandy smooth…

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Rock Sample:
The sample has black to green phenocrysts with a greenish white matrix. It has phaneritic grains with a aphanetic matrix. Phenocrysts are coarse to fined grained ranging from 0.1~1cm in size. There is a chalk like powder on the…

identification uncertain

PH-19 Thin Section in XPL.
Hand Sample:

All weathered faces of the rock show heavy traces of oxidation.

PH-13 Hand Sample.
Hand Sample:

Coarse grained pyroxenite showing heavy traces of oxidation on every weathered face of the rock. Large clusters (5-8 mm) of biotite appear throughout the rock.

PH-8 Hand Sample.
Hand Sample:

Rock is comprised predominately of a dark fine grained matrix. Some specimens have minor amounts of pink K-feldspar. Clusters of biotite (~1 cm in diameter) appear on one face of the rock.

Pyroxenite
Coarse pyroxenite, with traces of nepheline. This is the freshest pyroxenite that was found. It occurs near the nepheline syenite body in the eastern part of the complex.

Pyroxene-quartz-plagioclase gneiss
This specimen consists of 50-60% andesine, 20-30% quartz, and minor pyroxene and hornblende. Associated with this lithology are 2-6 inch layers of pyroxene-plagioclase granulite and amphibolite. It is believed that the Royal Mountain Member gneiss…

Kingdom: Animalia Phylum: Mollusca Class: Cephalopoda Subclass: Ammonoidea Order: Family: Genus: Species:

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Rock Sample:
The color is mainly a very dark green to dark grey. Some parts of the rock exhibit greasy luster. There are some tannish white spots and some slightly larger dark brown spots. The tannish white mineral reacts with acid. There are dark…

Hand Sample
Hand Sample: Aphanitic light gray vesicular pumice. Sample has incredibly low specific gravity due to abundant vesicles. Vesicles range in size from less than 0.1cm to 0.3cm. Some vesicles on cut face appear to be filled in with a lighter material.…

Hand Sample
Hand Sample: Glassy, dark gray, vesicular pumice. The sample contains many small pieces of the pumice, ranging from 0.03cm to 1.5cm in diameter. Chunks of glassy pumice and volcanic ash compose sample.
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