Browse Items (1651 total)

Very fine grained sandstone and silty shale noted between shale and dark, fine grained sandstone (sample 4 &5).

Thin Section:
Very fine sized sub rounded grains of pyroxene, quartz, and feldspar in a calcic matrix.

Shale, foliated, and bearing organic matter, from the interbeds between sandstone layers. Fine grained laminated sands between shales were uncollectible, but present. Friable and fragile.

Thin Section:
Very fine to fine grain, poorly sorted…

Sandstone with ripple marks and cross bedding and strong flute casts along surface indicating mid-high energy. Poorly sorted coarse sandstone with ripple marks, cross bedding and strong flute casts, as well as small pebbles that vary from angular to…

Collected from blocks moved during road construction. Have been moved perhaps 200 yards. More quartzite and igneous and crystaline metamorphic rocks than at Sternenberg sampling site. Thin Section Coarse to fine (7-.1 mm) poorly sorted grains of…

Porphyritic texture with large (>0.5 cm) euhedral garnets in a fine grained, green matrix shows serpentinization, one side containing mass of light colored transloucent pyroxcene; contains pyroxcene, plagioclase, olivine.

Thin Section.
Large…

Dark grey to black, aphanitic texture, fine grained matrix, smooth texture, euhedral light-colored garnets, pyroxene and garnet cystals in thin section show a yellow border in plain polarized light, additional long spindly pyroxene crystals visible…

Dark grey to black peridotite, phaneritic texture, containing numerous phenocrysts with a soft grey to white color. Small crystals of olivine visible in hand sample, characterized by a darker color than the surrounding rock and a more glassy luster,…

Dark colored phaneritic peridotite containes micas, garnets, olivine pyroxene and plagioclase all visible from hand sample. Sample is speckled with light colored material and larger crystals of pyroxcene, olivine and michas visible in hand sample,…

Hand Sample: Holocystalline, phaneritic, medim-grained granitoid with subhedral grains of smoky quartz, plagioclase feldspar, potassium feldspar, and biotite. Weathering to red-yellow on some surfaces.

Hand Sample: Holocrystalline, phaneritic, porphyritic, diorite with quratz crystals up to 3mm in diameter set in a field of smaller light gray, and dark gray crystals. Some small oxidized pyrite crystals. Very weathered on two sides to orange yellow…

Hand Sample: Holocrystalline, phaneritic, medium-grained granitoid with an abundance of alkali feldspar. Other minerals include quartz and biotite. Some chemical weathering has produced a white coating.

Hand Sample: Holocrystalline phaneritic, porphyritic and granophyrite rich in alkali feldspar. Larger crystals or pockets of biotite and quartz also present. Rock is weathered to orange brown. Contact on one side with dark black-brown quartz-rich…

Hand Sample: Holocrystalline, phaneritic, medium-grained granite composed predominantly of smaller alkali feldspar crystals with larger crystals of smoky quartz, biotite, and plagioclase feldspar

Hand Sample: Holocrystalline, phaneritic, fine-to-medium-grained quartz monzonite. Mineralogy includes large plagioclase laths up to 8mm in length, quartz, alkali feldspar, biotite. Very large crystals of a dark material up to 3cm in length.…

Hand Sample: Hypocrystalline, porphyritic, diabase with subhedral plagioclase and alkali feldspar (weathered to green) crystals approximately 1cm in length. Matrix is brown-black color. Weathered to white. Intensive weathering on one side to light…

Hand Sample: Holocrystalline fine-to-medium-grained phaneritic rhyolite with quartz, biotite, and plagioclase crystals generally no larger than 2mm. Weathers to brownish-orange.

Hand Sample: Holocrystalline, coarse-grained, phaneritic granite with dominant alkali feldspar crystals, as well as quartz and plagioclase feldspar. Veins or pockets of dark brown-black material dispersed intermittently.

Hand Sample: Aphanitic brown-black basalt with microcrystalline inclusions of quartz and alkali feldspar. Weathers to yellow orange. Part of a dike cross cutting granite at the Cornwall Quarry.

Hand Sample: Porphyritic diabase with light crystals in a dark-grey-to-black groundmass. Plagioclase 45%, Pyroxene 45%, Hornblende 5%, Olivine and Biotite 5%

Hand Sample: Hypocrystalline, porphyritic rhyolite. 20% subhedral to anhedral biotite, quartz, and microcline (sanidine) phenocrysts. 80% grey-brown groundmass. Massive.