Submitted by Raven Mueller on Wed, 2014-07-09 08:49
Stone Type (Commercial): 
Physical Data
Munsell Color(s): 
Stone Type (Lithologic): 
Grain Size: 
Very Fine
Petrographic Description: 

Specimen: 2013-012

This specimen is a gray slate. The color of the specimen suggests significant ferromagnesian and possibly graphite mineral presence. Owning to the aphanitic nature of the material, many of the constituent minerals in this specimen cannot be identified through microscopy. Visible Quartz/feldspar grains are very rare with a maximum dimension of .06 mm, most are smaller. Various species of mica presumably form the majority of the specimen’s fabric. Biotite comprises approximately 15 percent of slide area. Identifiable crystals of biotite have a maximum dimension of .3 mm. Other species of mica have a maximum dimension around .15 mm. Much of the biotite is oriented such that the cleavage plain is parallel to the slide surface and shows preferential elongation orientation. Carbonate minerals are very rare and occupy less than 1 percent of slide area with a maximum crystal dimension of about .12 mm. Most carbonate crystals have rhombohedral edges. Opaque minerals, likely magnetite, are common and occupy about 5 percent of slide area. Maximum crystal size is near .15 mm. No appreciable relict sedimentary features are visible on macro-inspection of the slide or under the microscope. The orientation of biotite crystals suggests the direction of maximum tectonic stress is perpendicular to the slide. More substantial foliation features and grain orientation preference would likely be visible in slides of alternative orientation.

7/14/15 MP


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Specimen ID
2013-012 Image of specimen in dry conditions. Finish: Natural cleftdownload image Close-up image of specimen in dry conditions. Finish: Natural cleftdownload image

Thin Sections

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Specimen ID Non-polarized Cross-polarized
2013-012 Specimen shown in non-polarized image Specimen shown in cross-polarized image


NOTE: Quarry locations are approximate.

James River Slate Company
State Route 652
23004 Arvonia , Virginia
United States
37° 41' 38.184" N, 78° 20' 44.988" W
Virginia US

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