Marble
This calcite marble is typical of most Adirondack metacarbonates. In the majority of instances, original dolomite has reacted to yield calcsilicates. Also present in these specimens are small, serpentinized droplets which may originally have been diopside or forsterite. Remnant grains of each of these minerals have been found in the marble. Accessory minerals are graphite, tourmaline, sphene, and sulfides. Adirondack marbles rarely occur by themselves. Rather, they tend to be interlayered with garnetiferous amphibolites similar to AD-10 (but not necessarily of igneous origin) and calcsilicates such as specimens AD-8 and AD-9. Quartzites and metapelitic layers occur with the marbles.
Thin section shows dolomite and serpentinized diospide
1980
Western Minerals Inc.
AD-7
Orthopyroxene gabbro
This specimen is typical of the saturated gabbros of the Adirondacks. The plagioclases are generally in the range of An₄₀ and the orthopyroxenes average close to En₆₀. Antiperthite is locally developed. Scattered grains of ilmenite and garnet occur. These gabbros may be genetically related to the anorthosites of the region.
Thin section shows plagioclase, orthopyroxene and hornblende.
1980
Western Minerals Inc.
AD-6
Megacrystic potassium feldspar gneiss
This lithology is characterized by 1-4 inch long megacrysts of microperthite in a groundmass of quartz, oligoclase, hornblende, orthopyroxene, garnet, and oxide. Although the contacts of this unit are everywhere conformable, the rock is believed to represent a metamorphosed igneous plutonic rock. Similar lithologies are present at other stratigraphic horizons in the Adirondacks. In the Northwest Adirondack Lowlands, Buddington referred to a similar lithology as the Hermon Granite Gneiss. The present samples would be more appropriately referred to as metamorphosed quartz-monzonites. Sporadic occurrences of orthopyroxene indicate that, locally at least, the lithologies are charnockitic.
Thin section shows plagioclase, quartz, hornblende and orthopyroxene.
1980
Western Minerals Inc.
AD-5
Pyroxene-quartz-plagioclase gneiss
This specimen consists of 50-60% andesine, 20-30% quartz, and minor pyroxene and hornblende. Associated with this lithology are 2-6 inch layers of pyroxene-plagioclase granulite and amphibolite. It is believed that the Royal Mountain Member gneiss represents a metamorphosed layered instrusion of overall tonalitic composition. Numerous internal features, such as xenoliths and possible slump structures, support this hypothesis.
Thin section shows plagioclase, quartz and hornblende.
1980
Western Minerals Inc.
AD-3
Adirondack Highlands, New York Western Minerals Supplementary Materials
OCR PDF of supplemental information for the Anorthosite-Charnockite Metamorphic Suite-Adirondack Mountains, New York collection.
Western Minerals Inc.
Western Minerals Inc.
1980
AD suite