REDUCTION SPOT IN WELSH SLATE - North Wales
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WELSH SLATE
Llanberis, North Wales
Llanberis, North Wales
The purple-coloured slates from North Wales sometimes have curious green spots. They are due to a chemical reaction between iron and organic matter in the original sediments, resulting in the loss of oxygen ('reduction').
The reduction spots are usually oval in shape because they have been stretched due to metamorphism. The ratio of the long and short axes being a useful guide to the amount of deformation that has taken place.
An unusual educational specimen.
Click on a picture for a larger image
Size: 8 x 6.5 x 0.8 centimetres
Weight: 113 grams
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