Browse Items (1651 total)

The predominant lithology of the Peck Lake Formation is a sillimanite-garnet-biotite-quartz-oligoclase gneiss with pods and lenses consisting of two feldspars and quartz (anatectic?). The lithology is widespread throughout the Adirondacks and may…

Minerals found in the calcsilicate facies contain quartz, diopside, enstatitic pyroxene, tremolite, calcite, and phlogopite. However, only a few thin sections have been found to contain all phases. In some specimens, the pyroxene is close to 100%…

This specimen is extremely rich in sillimanite. European geologists refer to such lithologies as "khondolites." This locality is very near some of the old graphite production sites west of Hague.
Thin section shows sillimanite, garnet, k-feldspar.

This rock type is characteristic of the light colored layers in the Sacandaga Formation. The mineralogy consists of garnet, feldspar, and quartz. Occasionally, sillimanite and skeletal oxides occur. Both plagioclase and microcline are present. Quartz…

This medium grained facies is one of a number of anorthositic sheets that intrude throughout the stratigraphic section of the southern Adirondacks. A chemical analyses of specimens from this outcrop yield results that are almost identical with…

The specimen was collected from the Oregon Dome Massif. The Oregon Dome is similar in all respects to the anorthosites described and analyzed by Buddington (1939) for the Adirondack High Peaks region (Marcy Massif). Texturally, the present specimens…

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,…

This specimen is typical of the metaigneous charnockitic rocks associated with the massif anorthosites in the Adirondacks. With variation in the quantity of modal quartz, the rock qualifies as either a charnockite or a mangerite. Quartz content is…

This granite post-dates deformation and metamorphism. Silver got a U/Pb zircon age of 1125 Ma. This is a most unusual rock type. This rock has small quantities of fayalitic olivine and ferrohedenbergite that occur with mesoperthite and quartz. It…

This particular charnockite has been described, with analyses by deWaard and Romey, "Petrogenetic Relationships in the Anorthosite-Charnockite Series of the Snowy Mountain Dome," in Anorthosite Volume, New York State Museum Memoir 18, p.307-315. In…

This specimen is representative of the pyroxene-plagioclase granulites that form from gabbros in the Adirondacks. This famous locality has been discussed, with analyses, by Buddington, 1939, Analysis 64L Table 15, and also in deWaard's 1965 type…

Chert with small dark riebeckite

green

Blueschist from an outcrop in a stream bed

Coarse-grained hornblendite (some specimens have a few garnets)

Thin-bedded greywacke and chert.

Reddish chert and shale

Slightly metamorphosed greywacke