Browse Items (1651 total)

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Hand Sample:

Three hand samples from different facies were collected to represent this sample. Out of two of the largest samples one is a dark fine grained rock while the other is coarse grained. Both contain large (5-8 mm) clusters of biotite.

mostly hornblende

The Sacandaga Formation consists of a well layered series of dark granulites (AD-12) and leucogneisses (AD-13). Orthopyroxene is generally present in greater quantity than clinopyroxene. It is not known whether these rocks are metasedimentary or…

This rock type is considered to be the most mafic of all units found in the entire White Mountain Batholith.

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.

The locality near Northville, NY represents the only example of this assemblage that has been encountered to date (1980) in the Adirondacks. The original lithology is that of a typical olivine metagabbro. During granulite facies metamorphism,…

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No associated sulfides

fine grained trap with abundant fragments of brecciated syenite

Hand Sample: Aphanitic dark gray trachyte. Sample contains zones with abundant tiny vesicles (less than 0.1cm in diameter), however the majority of the sample does not contain any vesicles or phenocrysts.

Light gray

Trachytes are an igneous volcanic rock with an aphanitic or porphyritic texture. Alkali feldspar, low amounts of plagioclase and quartz or a feldspathoid are common in trachytes.

Dark, finer-grained

Sample from the beta member of the Toroweap formation. Sample is light tan-orangish with weathered surfaces.

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

A sample from the gamma member of the Toroweap Formation. It is an orangish-brown sample.
Both thin section images were taken at a 400x magnification.

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