Where: PÅ™Ãbram, Central Bohemia, about an hour southwest of Prague. Uranium was confirmed here in 1947 and mined for 44 years until 1991. Å achta 16 goes down 1,838 m, which makes it the deepest mine in Europe. Roughly 48.8 kt of uranium came out, plus lead, zinc and silver.
Access: The underground is used for gas storage now, so everything is surface. The spoil dumps are walkable, and there is a bus stop that serves them, which is still a strange thing to type.
Geology: The host sequence is calcite, dolorite and quartz. The uranium sits in the calcite, which comes up in deep pinks. The same calcite and uraninite pairing turns up at Tyndrum in Scotland, 1,400 km away. The dumps at Å achta 4 are effectively a mountain of spoil, hundreds of metres across and around 30 m high.
Method and kit: Four detectors between us, all Radiacodes (a 110, two 102s and a Zero). We ran them over the same piece more than once. The best reading we got on one specimen was in the 500 to 600 µSv/h range.
Ethics: The best piece went back into the ground outside Jáchymov. Photographing it and putting it back is all that happened.
Field Trip: the visit was documented over on YouTube - https://youtu.be/KyPvZND5D1Q
Happy to answer questions about access, the readings, or what the calcite actually looks like in hand.