Browse Items (1651 total)

Schist with sparse garnet. This schist is darker and graphitic. It also contains biotite, chlorite, muscovite, feldspar, and quartz.

The thin section shows several large biotite grains with an included garnet, small quartz grains, muscovite, and…

A highly graphitic slate in the Walloomsac slates. Contains pyrite. This rock also contains biotite, chlorite, muscovite, quartz, ilmenite, and pyrite.

The thin section shows large biotite grains, and chlorite muscovite, and quartz. Fluid…

Kink fold in a slate from the Mt. Merino Member.

This rock is from the chlorite zone of the Barrovian metamorphic sequence (low metamorphism).

The graywacke facies in the Mt. Merino member (where sample 4 also comes from). Graywacke is a hard, dark-colored sandstone. This sandstone represents a similar rock to the protolith for the quartzite of sample 10.

The thin section shows quartz,…

Green shale of the Indian River member of the Normanskill formation. This shale contains muscovite, chlorite, plagioclase, and quartz.

The thin section shows quartz and biotite with some minor opaques.

This rock is from the chlorite zone of the…

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

Hand Sample: Aphanitic light gray nephelinite containing some melilite. Melilite is the white minerals that range in size from 0.1 to 0.5cm. Sample contains numerous small sized (less than 0.05cm) vesicles that are evident on the cut face.

Hand Sample: Aphanitic medium gray nephlenite. White intergrowth crystals are common throughout the sample and form long strands (approx. 0.6 - 1cm in length) on sides of sample. Sample contains some melilite.

Hand Sample: Aphanitic dark gray vesicular basalt. Vesicles are common throughout sample and range in size from 0.1 to 3.5cm in diameter. Individual olivine crystals are found throughout the sample and range in size from 0.1 to 0.4cm in length.

Hand Sample: Aphanitic dark gray vesicular basalt. Sample contains numerous vesicles ranging in size from less than 0.05cm to 1.5cm. Individual olivine crystals can also be found throughout the sample.

Hand Sample: Microcrystalline vesicular, dark-gray to black scoria. Vesicle size varies throughout the sample, ranging from larger circular vesicles with a diameter of approx. 1.5 cm on one surface and small vesicles (less than 0.1cm in diameter) on…

Hand Sample: Natural surface of sample is dark in color with smooth texture. Cut face reveals blocks of peridotite and dunite held together with a thin layer of lava cement. Sample has high specific gravity.

Hand Sample: Lapilli tuff containing pieces of pumice (HA-23) and trachyte obsidian (HA-22) ranging in size from 0.1cm to 1.5cm. Clasts are held together in light-colored ash. Sample surface crumbles when handled. Lapilli describes the size of the…

Hand Sample: Aphanitic light gray vesicular pumice. Sample has incredibly low specific gravity due to abundant vesicles. Vesicles range in size from less than 0.1cm to 0.3cm. Some vesicles on cut face appear to be filled in with a lighter material.…

Hand Sample: Aphanitic dark gray trachyte. Sample contains zones with abundant tiny vesicles (less than 0.1cm in diameter), however the majority of the sample does not contain any vesicles or phenocrysts.

Hand Sample: Aphanitic light gray vesicular basalt with large olivine crystals. Olivine phenocrysts range in size from single crystals approx. 0.1cm in diameter to clusters of olivine as large as 1cm in diameter. Vesicles throughout the sample are…

Hand Sample: Aphanitic light gray hawaiite. Sample contains sparse vesicles that are generally 0.1cm or less in diameter.

Ankaramites are dark porphyritic basalts that contain abundant pyroxene and olivine phenocrysts. Lesser amounts of biotite, and plagioclase may also be present.

Trachytes are an igneous volcanic rock with an aphanitic or porphyritic texture. Alkali feldspar, low amounts of plagioclase and quartz or a feldspathoid are common in trachytes.