Platt Collection 24/02/2004—22/10/2020

Photomicrographs of the main practical reference sets compiled by John P Platt. A work in progress - the aim is to illustrate and annotate most of the material used in the practical classes.
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Practical 1: GP-10 GP-10. Cambrian quartzite, Skye. General view, 1.5 cm x 1 cm, crossed polars. Many millimetre-sized grains still show their sedimentary character, with rounded...
Practical 1: GP-10
Practical 1: GP-10 GP-10. Cambrian quartzite, Skye, crossed polars. Strong undulose extinction, but without clear subgrain boundaries, shown by large grain left of centre. Other...
Practical 1: GP-10
Practical 1: GP-10 GP-10. Cambrian quartzite, Skye, crossed polars. A variety of grain shapes: the rounded grain right of centre probably preserves its detrital shape; other...
Practical 1: GP-10
Practical 1: GP-10 GP-10. Cambrian quartzite, Skye, crossed polars. Narrow zone running across the image is probably related to fracturing with some fluid input: its track across...
Practical 1: GP-10
Practical 1: GP-11 GP-11. Valdness Sparagmite (Late Precambrian), Norway. General view, 1.5 cm x 1 cm, ordinary light. Sedimentary texture still apparent at this scale. Opaque...
Practical 1: GP-11
Practical 1: GP-11 GP-11. Valdness Sparagmite (Late Precambrian), Norway. General view, 1.5 cm x 1 cm, crossed polars. Undulose, patchy and irregular extinction seen in the larger...
Practical 1: GP-11
Practical 1: GP-11 GP-11. Valdness Sparagmite (Late Precambrian), Norway. Large grain centre right shows strong undulose extinction, with conspicuous deformation lamellae...
Practical 1: GP-11
Practical 1: GP-11 GP-11. Valdness Sparagmite (Late Precambrian), Norway. Large quartz grain right of centre shows very strong undulose extinction, in contrast to oval feldspar...
Practical 1: GP-11
Practical 1: GP-11 GP-11. Valdness Sparagmite (Late Precambrian), Norway. Note the contrast in internal deformation between feldspar (top) and quartz (centre left), and also the...
Practical 1: GP-11
Practical 1: GP-11 GP-11. Valdness Sparagmite (Late Precambrian), Norway. The early stages of recrystallisation within and at the margin of a quartz grain. Width of view 0.8 mm,...
Practical 1: GP-11
Bani Hamid Quartzites