In Hasle Lystskov there is an idyllic little forest lake between the trees – Rubinsøen. The lake’s name has nothing to do with gemstones, the name comes from the minerals in the soil that made the lake’s water coloured with a ruby red hue, which however gradually disappeared as the mine filled with water.

The reason why a coal mine was made in the forest was that World War II was going on and coal was needed for fuel, and since coal had been dug in the area earlier, it was thought that this quarry could supply Denmark with coal during the war. Unfortunately, they started too late, only in the summer of 1943 and the yield in the following 4 years was not greater than what was spent on Bornholm in less than 1 year. The yield was only 37,000 tonnes, so it was a huge failure.

The Anker brothers were the contractors for the project. The excavation work, carried out here by excavators, was an open pit, where the people worked under the open sky, unlike what they had done in the earlier coal mines in Hasle. The Hasle colliery was the only one in Denmark and employed 60 people.

What the machines dug up was loaded onto a tipper that travelled on rails to the coast, where a plant separated sand, clay and gravel from the litter. The waste products were poured over the slope, the result was the Kultippen, a completely barren area. The coal was transported by ship to Zealand.

The Bornholmers were happy though, they went down to the beach and picked up the litter and used it at home in the stove.

The coal that was brought up from the ground was black coal and of quite good quality with a good calorific value. The fault itself had a diameter of 200 m and a depth of 37 m was reached when the fault was closed in 1948.

Today you can’t see that it’s an old coal mine, nature has taken over again and nicely camouflaged the break. However, it is possible to see where the tippers have been, as there is a depression in the woods towards the hilltop on the coast.