BETA

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Vermont Black

Submitted by Raven Mueller on Tue, 2014-07-08 10:12
Stone Type (Commercial): 
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Available
Physical Data
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Munsell Color(s): 
Geology
Stone Type (Lithologic): 
Grain Size: 
Fine
Very Fine
Petrographic Description: 

Specimen: 2014-009

This specimen is a gray slate. The color of the specimen possibly suggests the presence of graphite dust. Owning to the aphanitic nature of the material, many of the constituent minerals in this specimen cannot be identified through microscopy. Quartz/feldspar 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.25 mm and less in length and show some orientation preference. Carbonate minerals variably occupy between 30 to 50 percent of slide area with a maximum crystal dimension of about .1 mm. Most carbonate crystals have rhombohedral edges. Opaque minerals are rare and make up less than 1 percent of slide area. Clearly relict sedimentary features are visible on macro-inspection of the slide in the form of faint banding. These are visible under the microscope by the increased presence of opaque minerals, a decrease in the prevalence of carbonate minerals, as well as a decrease in the translucency of the aphanitic component. Overall the lack of more significant grain elongation and orientation prevalence indicates very low grade metamorphism. This may be due to the slide’s orientation, which is perpendicular to the likely direction of maximum tectonic stress.

7/14/15 MP

Images

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Specimen ID
2014-009 Image of specimen in dry conditions. Finish: Natural cleftdownload image

Thin Sections

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Specimen ID Non-polarized Cross-polarized
2014-009 Specimen shown in non-polarized light.download image Specimen shown in cross-polarized light.download image

Quarry

No quarry information available for this stone.

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