Browse Items (1651 total)

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 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: 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 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: 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 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: 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 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…

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…

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

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.

Macroscopic: Grey garnet, biotite and chlorite bearing quartzite. Likely protolith is a low-Al quartz-rich sandstone bed. Microscopic: Abundant quartz crystals accompanied by chlorite and biotite. Thin section pictures in XPL unless otherwise noted…

Quartz Monzonite from the Kinsman Quartz Monzonite unit. Thin section shows quartz, potassium feldspar, plagioclase, biotite, muscovite, and myrmekitic texture. Hand sample contains quartz, feldspars, and micas.

Quartz Monzonite from the Kinsman Quartz Monzonite unit. Thin section contains lots of plagioclase in addition to biotite and quartz. Hand sample contains feldspars, quartz, and biotite.

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

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.

From the Concord Granite. Thin section contains plagioclase, potassium feldspar, quartz, biotite, and muscovite. Hand sample is finer grained and contains feldspars, quartz, and micas.

Ferrohypersthene Garnet Biotite Tonalite from the Spaulding Quartz Diorite. Some samples are fairly weathered. Thin section contains garnet, biotite, quartz, and plagioclase. Hand sample shows garnet, biotite, quartz, feldspars, and evidence of…

Spotted Spaulding Granite, member of the Spaulding Quartz Diorite. Part of an irregular sill, not the major facies. Spotted appearance, extends through more mafic facies. Thin section contains quartz, alkali feldspar, plagioclase, mica, and…

Hypersthene Quartz Diorite from the Spaulding Quartz Diorite. Thin section contains pyroxene, quartz, biotite, plagioclase, and alkali feldspar. Hand sample shows micas, quartz, feldspars, and pyroxene.