Browse Items (25 total)

  • Collection: (ADK) Anorthosite-Charnockite and Metamorphic Suite --
    Adirondack Mountains, New York

Wollastonite-garnet-diopside
This unique rock contains white crystalline wollastonite, brown grains of andradite garnet, and green diopside. Specimens courtesy of R.R. Bauer, plant manager of NYCO MInes (1980). McLelland reports some grossularite in addition to andradite.

The…

Woolen Mill gabbro
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…

Charnockite
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…

Fayalite-ferrohedenbergite-mesoperthite granite
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…

Mangerite-charnockite
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…

Two Pyroxene-spinel metagabbro
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,…

Anorthosite
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…

Tennantville gabbroic anorthosite
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…

Garnetiferous leucogneiss
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…

Sillimanite-garnet-quartz-feldspar gneiss
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.

Calcsilicate rock
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%…

Sillimanite-garnet-biotite-quartz-plagioclase gneiss
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…

Charnockite
This charnockite is similiar to most of the Adirondack charnockites that occur interlayered with other metastratified units. Like its analogues, the Canada Lake charnockite shows conformable realationships with enveloping units. Mineralogically,…

Quartzite
This specimen is typical of the 5-10 foot thick coarse grained layers of glassy quartzites that comprise this formation. In most instances the quartzites are about 90% quartz. Feldspar and garnet are encountered locally. This is presumed to be the…

Coarse anorthosite
This coarse-grained specimen is typical of the massive, homogeneous anorthosite that occurs within the Marcy Massif and underlies the High Peaks region of the Adirondacks. The anorthosite from Route 3 is best represented by analyses 5-L and 8, Table…

Garnetiferous olivine metagabbro
This specimen is typical of the olivine metagabbros that occur throughout the Adirondacks. These rocks are of great petrologic interest for they contain classic examples of garnet coronas and spinel-clouded plagioclase. Note the preservation of…

Quartz-microcline-diopsite gneiss
This specimen displays an unusual and distinctive lithology that occurs primarily in lower, marble-rich units (for example, the Cedar River Formation).
Thin section shows quartz, K-feldspar and clinopyroxene.

Two-pyroxene-plagioclase granulite
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…

Garnetiferous amphibolite
This specimen is similar to the famous garnet deposits at Barton Mines at Gore Mountain. The garnets at Gore Mountain can attain diameters of 3 feet. At the Speculator road cut, garnet of 8-10 inches in diameter have been found, but smaller examples…

Diopsidite
Pods and lenses of green diopsidite commonly occur along with the marbles. They are often composed of over 90% diopside.
Thin section contains diopside.