Another interesting use for slag is starting to sprout out of France. In the north of the country where its mining and industrial industry has now been abandoned all that remains are the small mining villages and the colossal slag hills or “terrils”.

These 150 metre high slag hills which were once despised by the public are now seen as symbols of a proud industrial heritage. In fact the hills are now recognised as a world heritage site by UNESCO.

The hills have recently started sprouting small plants, shrubs and even forests. Although the quality of the soil is not the best it is believed that the plants are having success due to the sorting methods of the miners in the 18th and 19th Century. In the past the slag was sorted by hand, which resulted in some coal and other materials being added to the hills with the slag. As time passed and the coal began breaking down the elements and minerals combined with the crumbling slag, creating a soil, while not perfect is ‘good enough’.

Henri Jammet, a wine-grower who lives below the hills has planted and successfulls harvests a green grap vineyard. Mr Jammet said that "People here were very surprised, but the wine is great. The terril is stony - it drains well because it is on a slope; the earth is black which keeps in the warmth; and we face south - all things that help the vines," says Jammet.

"Obviously the soil is poor - but that is good. Vines need to struggle in order to bring out the best in the grape. Our wine is sharp because they don't have the sun up here to reduce the acidity - and it's got the proper Chardonnay citrus notes." To read more about this incredible story, CLICK HERE!