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Garnet-bearing quartzite
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…
Garnet-biotite sericite schist
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…
Garnet-muscovite bearing granitic pegmatite
Macroscopic: Garnet-muscovite bearing granitic pegmatite. Visible, green beryl may be present as beryl is often associated with pegmatites. The mineralogy is typical of sedimentary protolith granites which supports the hypothesis that the basement of…
Garnet-rich Quartz-Monzonite
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…
Hand sample shows large biotites, plagioclase, and quartz.
Thin section…
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…
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…
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…