Buckingham

Specimen: 2014-084-1
This specimen is a gray slate. The color of the specimen suggests significant graphite dust presence. Owning to the fine grained 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 .08 mm, most are smaller. Various species of mica and clay presumably form the majority of the specimen’s fabric, but these are generally too small to be individually perceived. Visible crystals of mica (biotite) are mostly .55 mm and less in length and comprise about 5 percent of slide area. Visible mica crystals show orientation preference with a cleavage plane parallel to the thin section surface and elongation perpendicular to the short axis of the slide. Opaque minerals are present with a modal size around .15 mm and comprise about 3 percent of slide area. Carbonate minerals are not visible. Overall the lack of more significant grain elongation and orientation prevalence indicates very low grade metamorphism. This may be partly due to the slide’s orientation, which is perpendicular to the likely direction of maximum tectonic stress.
MP 9/4/2015

Specimen: 2014-084-2
This specimen is a gray slate. The color of the specimen suggests significant graphite dust presence. Owning to the fine grained 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 .04 mm, most are smaller. Various species of mica and clay presumably form the majority of the specimen’s fabric, but these are generally too small to be individually perceived. Visible crystals of mica (biotite) are mostly .5 mm and less in length and comprise about 5-10 percent of slide area. Visible mica crystals show orientation preference with a cleavage plane parallel to the thin section surface and elongation acute to the short axis of the slide. Slight pressure shadows are present around larger crystals of biotite, and this is the location of relatively larger quartz/feldspar. This imparts a porphyroblastic appearance to the slide. Opaque minerals are present with a modal size around .12 mm and comprise about 3 percent of slide area. Carbonate minerals are not visible. Overall the lack of more significant grain elongation and orientation prevalence indicates very low grade metamorphism. This may be partly due to the slide’s orientation, which is perpendicular to the likely direction of maximum tectonic stress.
MP 9/4/2015

Specimen: 2014-084-3
This specimen is a gray slate. The color of the specimen suggests significant graphite dust presence. Owning to the fine grained 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 .12 mm, most are smaller. Various species of mica and clay presumably form the majority of the specimen’s fabric, but these are generally too small to be individually perceived. Visible crystals of mica (biotite) are mostly .55 mm and less in length and comprise about 5 to 10 percent of slide area. Visible mica crystals show orientation preference with a cleavage plane parallel to the thin section surface and elongation acute to the short axis of the slide. Slight pressure shadows are present around larger crystals of biotite, and this is the location of relatively larger quartz/feldspar. This imparts a porphyroblastic appearance to the slide. Opaque minerals are present with a maximum size around .36 mm and comprise about 3 percent of slide area. Carbonate minerals are not visible. Overall the lack of more significant grain elongation and orientation prevalence indicates very low grade metamorphism. This may be partly due to the slide’s orientation, which is perpendicular to the likely direction of maximum tectonic stress.
MP 9/4/2015