One of the biggest questions we have in terms of our work on mine dumps, is not just how much Au, In, Bi, Co, Cu, etc. they contain, but in fact how big they are. After all if the thing is super rich in a critically needed metal, but the dump is only 2 square meters it isn't really going to be of much use. However, it is often (almost always?) to get a good idea of the size of these 200+ year old waste dumps, or even where they exactly are.
To kick off our new grant in collaboration with the Geosphere Austria (aka Austria Geo Survey), we re-visited a mine dump in the Hohen Tauern to see if we could use any geophysical methods to find and estimate the size of a well known tailings pile. This is a first test case, where we know the size and location of the mine dump from old mine documents, the hope was that the geophysics could get the 'right' answer in this first test case.
Dr. Thomas Angerer (head of the raw materials division of the Geosphere) studying the old (now digitized) mining documents, to figure out where to best do our geophys transect.
The Geopshere geophys team hard at work setting up the first (and in the end only) geoelectric survey of the week. Unfortunately, software crashed, a failed generator, and torrential rain meant that this was to be the only successful imaging we did...
Not one to let bad weather, and failing generators get in the way, we took the opportunity while the 6 hour geoelectric survey was running to collect from samples for Eileen's thesis from an old (medieval) mine. The last few meters up to the mine where so steep that we needed a rope to get up (luckily some mineral collectors had left one for us).
Whenever I go into these medieval mines, I am always shocked how anyone could have worked in such tight conditions for 12+ hours a day, with only candlelight (if they were lucky) to see by. Candles were generally considered too expensive by the foremen, so the miners often were used thin strips of pine that were dipped in oil. Must have been a smoky hellscape.
Here Thomas is standing next to some 'shremspuren,' aka the evidence of mine adits that were hewn by hand....... Some poor saps (usually they worked in teams of two) had to dig away one cm at a time, for years and years. On average medieval miners in Austria where expected to make 3-8 cm of progress a day (depending on the bedrock).
Come on Eileen!! Eileen traversing over a water filled adit, not really water you want to go swimming in... My claustrophobic self voted to turn around at this point, but Eileen was insistent it was safe. What's an adviser to do, when he has such motivated students, gotta get that sample =)
Finally, what we came for!!! Here I am for scale pointing at a rich chunk of ore in the hanging wall.
Thomas hard at work trying to get the chunk of ore out. Took the better part of an hour to get a good piece. Makes you really appreciate the physical work the old miners had to endure. Safety note: I promise we where wearing safety glasses, but they were so covered in mist, sweat, and mud that Thomas insisted on taking them off for the photo-op.
With our sample in hand Thomas and I pause for a view of the scenery. Unf. not enough room at the top for a group selfie =(
Obligatory group photo op. Unf. not in the mine we visited on the day, as it was too narrow to for a photo of us all together. This was taken the day prior in the 'modern' (1910s) Imhoffstollen. Safety note: this mine is illegal to enter without the express permission of the company that maintains the old adits and retains the mining rights. We were lucky enough to have a representative of the company with us, so we could have a quick look in.