Submitted by Raven Mueller on Wed, 2014-07-09 08:37
Stone Type (Commercial): 
Physical Data
Munsell Color(s): 
Stone Type (Lithologic): 
Grain Size: 
Very Fine
Petrographic Description: 

Specimen: 2013-006

This specimen is a gray slate. The color of the specimen suggests significant graphite dust presence. Owing to the aphanitic nature of the material, many of the constituent minerals in this specimen cannot be identified through microscopy. Quartz/felspar grains are common with a maximum dimension of .1 mm, most are smaller. Various species of mica presumably form the majority of the specimen’s fabric, but these are generally too small to be individually perceived. Identifiable crystals of mica are mostly .1 mm and less in length and show some orientation preference. Carbonate minerals are also extremely abundant and vary in contribution across the slide between about 20 to 60 percent of slide area. Many of these carbonate crystals have rhombohedral edges, with a maximum crystal dimension around .08 mm. Clearly relict sedimentary features are visible on macro-inspection of the slide in the form of banding. These are also visible under the microscope as alternating dark and light areas that are largely reflective of carbonate mineral concentration and opaque mineral presence. There are also opaque spherical inclusions with a max dimension of .06 mm that may be remnant sedimentary features. Overall the lack of more significant grain elongation and orientation prevalence indicates very low grade metamorphism. This may due to the slide’s orientation, which is perpendicular to the likely direction of maximum tectonic stress.

7/14/15 MP


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Specimen ID
2013-006 Image of specimen in dry conditions. Finish: Natural cleftdownload image Close-up image of specimen in dry conditions. Finish: download image

Thin Sections

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Specimen ID Non-polarized Cross-polarized
2013-006 No image available.


NOTE: Quarry locations are approximate.

Vermont Structural Slate Quarry
620 Saltis Rd
05764 Poultney , Vermont
United States
43° 33' 42.876" N, 73° 14' 7.26" W
Vermont US

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