Submitted by Raven Mueller on Wed, 2014-07-09 08:43
Stone Type (Commercial): 
Physical Data
Munsell Color(s): 
Stone Type (Lithologic): 
Grain Size: 
Very Fine
Petrographic Description: 

Specimen: 2013-009

This specimen is a purplish slate. The color of the slate is imparted by a high iron content that likely includes hematite, limonite, and siderite. Owing to the aphanitic nature of the material, there are few identifiable crystal grains in this specimen. Quartz/felspar grains are common with a maximum dimension of .15 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 .05 mm and less in length and show some orientation preference. Carbonate minerals are also extremely abundant and compose around 30 percent of the specimen’s fabric. 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. 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


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Specimen ID
2013-009 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
2013-009 Specimen shown in non-polarized image Specimen shown in cross-polarized image


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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