Browse Items (1651 total)

Granite, dark facies, from the Concord Granite. Thin section contains quartz, plagioclase, potassium feldspar, and biotite. Hand sample shows lots of quartz and feldspars with dark biotite.

Hornblende Gabbro-Diorite from the Spaulding quartz diorite. Thin section contains hornblende, plagioclase, and quartz. Hand sample contains hornblende, plagioclase, and quartz.

Garnet-rich quartz monzonite from the Kinsman Quartz Monzonite. Garnets are replaced partly by biotite. Some of the garnet forms pods and boudins. Similar sample to NH-9.
Hand sample shows large biotites, plagioclase, and quartz.
Thin section…

Rock Sample:
The sample is metamorphic. It is green to light-green in color. There are very course grained tabular zones of metamorphism (12x4cm) and light to dark layering with non-uniform shapes and patterns. The grains are aphanitic. The…

Macroscopic: Biotite, muscovite schist. The biotite has begun retrograding to chlorite. There is a mineral zone consisting of garnets present in the handsample. Microscopic: Abundant foliated biotite/sericite and quartz. Large amphibole phenocrysts…

Rock Sample:
The sample is fine-grained, and the majority of the rock is dark grey in color. There is a 2.5x4cm white crystal formation on the upper edge of the sample. There are fractures running through the sample. There is some chemical…

Macroscopic: Porphyroblastic amphibole in epidote, chlorite, and garnet calcsilicate rock. This sample represent the metamorphism of calcarious concretions in beds of quartzite to a schist. The formation this samples comes from has considerable…

Rock Sample:
The sample is pinkish gray with brown to green phenocrysts. There are fine-grained to medium-grained phenocrysts (0.5~5mm in length). There is a dark-brown to orange coating, which is evidence of chemical weathering due to oxidation. …

Macroscopic: Staurolite, garnet, biotite porphyroblastic, chlorite bearing, muscovite schist. Both garnets and staurolite are idiomorphic with the former highly poikiloblastic. The foliation in the schist bends around the porphyroblastic phases…

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…

Macroscopic: Biotite, muscovite schist. This sample was a part of a roof pendant, or a piece of rock the surrounded a batholith. Likely part of the silimanite zone. Microscopic: This sample under thin section displays an almost entirely mica and…

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…

Macroscopic: Mesocratic fibrolitic double micaceous pinstripped gneiss. High reflectivity denotes a high concentration of foliated micas. Migmatized texture indicates of the rock indicates incipient melting. Microscopic: This sample contains…

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…

Macroscopic: Leucocratic biotite, muscovite, sillimanite gneiss. A banded gneiss characterized by leucocratic minerals. Microscopic: thin section shows an abundance of muscovite and quartz. Thin section pictures in XPL unless otherwise noted in the…

Macroscopic: Andalusite, biotite, garnet, muscovite, chlorite schist. Heavily weathered exterior due to divets and altered nature. High abundance of foliated mica. Microscopic: The andalusite, biotite, and garnet are porphyroblastic with andalusite…

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…

Macroscopic: In this Chiastolite slate, the andalusite has retrograded to sericite. Microscopic: Strongly foliated sericite. Thin section pictures in XPL unless otherwise noted in the title of the picuture. Thin sections are 3mm across.

Rock Sample:
The sample is a dark greenish blue with brown layering. On one side of the sample there is a sand-like residue that is tan in color. The sample is aphanitic and possesses micro-folds. The sample appears to have experienced some…

Macroscopic: An andalusite, biotite schist with large and abundant garnet porphyroblasts. Low grade of metamorphism. Microscopic: Large andalusite and cordierite phenocrysts within very fine grained matrix. Thin section pictures in XPL unless…