Unfading Green

Submitted by Raven Mueller on Tue, 2014-07-08 10:14
Stone Type (Commercial): 
Physical Data
Munsell Color(s): 
Stone Type (Lithologic): 
Grain Size: 
Very Fine
Petrographic Description: 

Specimen: 2014-010

This specimen is a green slate. The color of the specimen possibly suggests the presence of chlorite. 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 .25 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.3 mm and less in length and show moderate orientation preference. Carbonate minerals are not apparent in this slide. Opaque minerals are rare and make up less than 1 percent of slide area. There is a relict void or some other structure filled with what are likely chlorite group minerals and opaques that is approximately 2.25 by 1 mm. 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 prevalence of quartz/feldspar and the translucency of the aphanitic component. Overall, the lack of more significant grain elongation and orientation prevalence indicates low grade metamorphism. This may be due to the slide’s orientation, which is perpendicular to the likely direction of maximum tectonic stress.
7/16/14 MP


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Specimen ID
2014-010 Image of specimen in dry conditions. Finish: Natural cleftdownload image

Thin Sections

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Specimen ID Non-polarized Cross-polarized
2014-010 Specimen shown in non-polarized image Specimen shown in cross-polarized image


NOTE: Quarry locations are approximate.

Calder Quarry
United States
Vermont US

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