Browse Items (1651 total)

flinty, columnar jointing, post-batholith volcanic

intrusive plug of quartz monzonite

Hand Sample: Porphyritic rhyolite with medium-grained potassium feldspar and plagioclase feldspar phenocrysts in a dark red-brown matrix. Weathers with an orangish tinge.

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: Aphanitic, pink-black rhyodacite. Sample contains alternating black and dark pink bands across face. Sample does not contain any vesicles or phenocrysts.

Rhodingitized gabbro dike in serpentinite. Chlorite, hydrogrossularia, diopside, prehnite, pumpellyite, vesuviane.

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Kingdom: Animalia Phylum: Echinodermata Class: Echinoidea Subclass: Regularia Order: Family: Genus: Species:

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Oblitic and Crinoidal Lithology.

Both thin section images were taken at a 400x magnification.

Fine-grained limestone with occasional fossil remains.

Both thin section images were taken at a 400x magnification.

Though listed as a limestone, this sample is best described as a conglomerate with calcite present in the matrix. This sample was collected from a bed of conglomerate lithology just below contact with Supai formation.

Both thin section images…

Reddish chert and shale

Red shale from the Indian River member of the Normanskill formation. This rock contains hematite, chlorite, muscovite, plagioclase, and quartz.

The thin section shows muscovite and biotite with some larger quartz grains visible and minor hematite…

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, 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.

Red jasper matrix with interescting veins of while quartz. Prominent physcial weathering, brittle areas fall apart to the touch. Several prominent fractures run through the rock, contributing to the weakened structure. Most fresh surfaces are reddish…