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A Geoscience Digital Image Library

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TitleTrachyte porphyry (Bostonite), Essex County, New York
DescriptionThis intrusive igneous rock is a reddish brown, felsitic rock with small feldspar phenocrysts (sodic orthoclase) in a matrix of feldspar and minor amounts of highly altered mafic minerals. The matrix feldspar is stained red by hematite. It sample is about 10 cm across.
ChronostratigraphyPost-Ordovician
LocationUSA ▹ New York ▹ Essex. Near Essex.
PhotographerJoseph Hartman. 2001-02-06.
CollectionWard’s Collection of Classic North American Rocks #15.
Key wordstrachyte, porphyry, bostonite, New York
Tech details768 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon micro lens.
GeoDIL number26
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