Combustion and red schists :
The coal tip is the result of numerous human activities. At first, miners who extracted the coal also went back up a big quantity of sluggish materials, evacuated to reach the veins of coal. These worthless materials were deposited on grounds without any economic interest.
Vast zones of deposits of materials entered combustion. Combustion of a coal tip is a complex phenomenon. Dusts and small pieces of coal, stemming from an incomplete sorting,were mixed with schists and coal stonewares on the deposite site. A fire nearby or the chemical reaction of pyrite of iron (exothermic oxidation) in the contact of the atmospheric oxygen caused the combustion. Then the coal tip releases heat and smokes.
Burning of black schists transformed them. As the transformation of clay into brick-built or into tile, the black schists became red. Much more solid and more resistant, red schists, become then very interesting for the road elevations. So as to coal tips often become stony quarry and are exploited again.
Reminder on "Earthcaches": There is no container or logbook on the given coordinates. Just visit the site and answer the questions by e-mail or by the Message Center.There is no need to wait for my reply, feel free to log immediately after. If the answers are incorrect, I will let you know. Happy EarthCaching!
To validate your visit:
1-. On the summit is a big rock, do you think it had been carried up here in a single block or not?
2-. Estimate the size of this big rock
3-. Take a handful of schist in your hands, what do you feel? Is it hard, crisp, light, heavy?
4-. What is the dominant color of the ground? Do you think the coal tip completely has burned?
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