Browse Items (1651 total)

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 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…

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

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…

This specimen is typical of the saturated gabbros of the Adirondacks. The plagioclases are generally in the range of Anâ‚„â‚€ and the orthopyroxenes average close to En₆₀. Antiperthite is locally developed. Scattered grains of ilmenite and garnet…

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…

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…

Albite, Na-amphiboles (from Mg-riebeckite to glaucophane, epidote, aegirinic pyroxene, chlorite, ilmenite, tspesphene, apatite, lawsonite. Pseudomorphic relations of the metamorphic paragenesis on the substituted primary phases. Sometimes lawsonite…

Sodic pyroxene, glaucophane, lawsonite, chlorite. Pseudomorphs of sodic pyroxene and glaucophane,chlorite on original augitic pyroxenes; pseudomorphs of lawsonite and glaucophane on original plagioclase.

Carbonates (calcite and dolomite), chlorites, garnets, diopside, epidote, serpentine, amphiboles. Very variable compositions in same hand specimen. The rock derives from metamorphism of oficalcitic rocks developed at very high pressures and medium…

Relics of augitic clinopyroxene, albite, actinolite, chlorite, clinozoisite, and sphene. Relics of the clinopyroxene of the original dolerite are in part substituted by chlorite and actinolite in a granoblastic and metablastic matrix of albite,…

Grossular-andradite garnet, diopside, chlorite, sodic pyroxene, vesuvianite, titansphene, opaques. Traces of primitive gabbroid structure with diablastic development of the newlyformed phases and pseudomorphs of sodic pyroxene on primary pyroxenes.…

Antigorite, magnetite, ankeritic carbonate, diopside, tremolite. A very marked subsequent foliation nearly completely obliterates a previous initial foliation.

Antigorite, magnetite, carbonates (ankerite), diopside, clinohumite, tremolite, chlorite. Rarely, pseudomorphs on primary pyroxenes may be recognized, though there is superimposition of various deformational phases.

Gabbro with hydrothermal "oceanic" processes and prehnite-pumpellyite metamorphic overprint.
Plagioclase, clinopyroxene, olivine, ilmenite. metamorphic paragenesis: albite, sericite, chlorite, hematite, sphene, carbonates. Well-preserved relics of…

Na-clinopyroxene (chloromelanite), almandine garnet, rutile, glaucophanic amphibole, harrisitic hornblende, epidote, ablite, chlorIte. Chloromelanite pseudomorphs on primary pyroxenes and chloromelanitic aggregates in plagioclase; granoblastic…

Doleritic basalt with metamorphic overimprinting in prehnite-pumpellyite facies.
Primary minerals: plagioclase, titanaugite, ilmenite, olivine.
Metamorphic paragenesis: albite, pumpellyite, prehnite, sphene, chlorite.

Serpentine (lizardite) with some structural deformation present.

Hyaloclastite of basalt with superimposed metamorphism in pumpellyite-prehnite facies.

Serpentinized peridotite with plagioclase, olivine, plagioclase, clino-pyroxene, chromite. Secondary minerals include hydrogrossuaria as well as serpentine, chlorite, prehnite.