Unfading Red

Submitted by Raven Mueller on Wed, 2014-07-09 08:41
Stone Type (Commercial): 
Physical Data
Munsell Color(s): 
Stone Type (Lithologic): 
Grain Size: 
Very Fine
Petrographic Description: 

Specimen: 2013-008

This specimen is a red slate. The color of the slate is imparted by a high iron content that likely includes hematite and limonite. There are few identifiable crystal grains in this specimen. Quartz/feldspar grains are common with a maximum dimension of .07 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 .035 mm and less in length and show some orientation preference. There are sphereical inclusions (circular in thin section) that may represent remnant sedimentary features. These have a maximum dimension of .4 mm, a minimum of .06 mm, and a modal range around .3 to .15 mm. Most of these are filled with what are likely replacement chlorite minerals. Several contain carbonate minerals in the process of being replaced. Hematitie and other opaque minerals often form envelopes around these structures. Clearly relict sedimentary features are visible on macro-inspection of the slide in the form of banding. These features are not easily perceived with microscopic inspection. 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
2013-008 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
2013-008 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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