Fluorite from Gastein
GREEN FLUORITE-OCTAHEDRON FROM THE GASTEINER TAL
This article is about a find in the Gasteiner Tal (Gastein Valley) in 2009 and 2010. To begin with, I will give you some basic information about the geography and the geology of the valley:
The Gasteiner Tal is located in the Pongau region in the federal state of Salzburg in Austria. It comprises the Naßfelder Tal (Nassfeld Valley) – coming from the Southwest – and the Anlauftal, which runs eastward. The Gasteiner Tal is about 40 Kilometers long. The two valleys, which constitute the Gasteiner Tal meet in Böckstein, a district of Bad Gastein, a famous touristic community in Austria. The main river is the Gasteiner Ache.
The Gasteiner Tal is the largest side-valley of the Salzachtal – the Salzach in turn being the main river of the federal state of Salzburg.
The valley itself has been secluded for centuries – up until the last century it was only accessible by small mountain trails and one narrow road. Traditionally, alpine agriculture, thermal springs and mining were crucial factors for the regional economy. Eventually it was the Alpine World Ski Championship of 1958 that was responsible for the development of active winter tourism.
Geologically speaking, the valley has its roots in the Ankogelgruppe (the highest elevation of which is the Hochalmspitze – with its summit at 3.360 meters above sea level) and the Goldberggruppe (highest peak is the Hocharn at 3.254 meters above sea level). Both are part of the main ridge of the Hohe Tauern, which is strongly glaciated in parts. A glacier of gigantic dimensions – it was about 1 kilometer thick – once formed the valley. The enormous bowlders, which the glacier has transported from the inner Tauern peaks can still be found today scattered throughout the countryside. The whole valley forms a great and impressive alpine landscape, which is inviting not only to look for minerals but also to linger, to hike and to explore the wildly romantic area.
Let us now turn our attention towards the actual discovery – the Hirschwald: this discovery has already been mentioned in the specialist literature many times and is well known to generations of collectors. Thus it is not actually a new discovery but rather a resurrection.
Here, the fluorite surfaces from time to time in hydrothermal veins. Several discoveries are known, which – time and again – have produced green octahedrons of up to 4 centimeters edge length – exceptional crystals with an edge length of over 5 centimeters are also known. The color is almost always of a pale green, the surface typically strongly etched. Mostly, the specimens are made of intensely chatty crystals, and the matrix forms a central gneiss complex.
We owe the resumption of collecting to my close friend Reinhold Bacher. Reinhold will probably be well known to many collectors – I have already described his work at the summit cleft at Weisseck in the Mineralogical Records (July-August Edition 2010) and Europe’s leading mineral-journal Lapis has published an article about a find of unique, highly esthetical berg crystals from the Zederhaustal, which also decorated the cover of Lapis journal in January 2011.
Reinhold initially visited the discovery for an on-site inspection. He quickly realized why the discovery had been buried in oblivion for decades or rather had fallen into obscurity. The finds became increasingly worse; the crystals were almost colorless, severely eroded and damaged – hence the interest had faded away. What had happened?
There is a simple answer to this question: generations of collectors had only worked at the in-situ rock. Already broken out rock was dealt with and layers of exposed rock were knocked off. Instead of following the fluorite band deeper, many chose the easier way and worked the surface instead of the more labor-intensive tunneling into the mountain.
As a result, the actual zone with fluorite was covered by a several meters high debris field. But when it is about fluorite, Reinhold has no sense of humor and doesn’t spare no pain. In a two-week act of force by several collectors, 4 to 5 meters of rubble were removed. Even a pulley was used in order to move the biggest rocks. Finally the collectors reached the initial fluorite band and began a real tunneling in order to follow the fluorite into the mountain.
Meanwhile we have reached the spring of 2010 – After several months of inactivity, to which winter, snow and ice had condemned us, both Reinhold and I were itching to go back to the mountains and to delve into a first round of collection. We met at the end of April in Tamsweg, Reinhold’s place of residence. Together with another friend we took off in the early morning towards Gastein, where we met with yet another collector who lives in Gastein. The four of us began ascending to the discovery. We had chosen the ideal time, since the discovery was already clear of snow. And, although we did not catch a day of bright sunshine, – considering this time of the year was particularly rainy in 2010 – we managed at least to stay reasonably dry.
The ascent led us across a once thickly wooded precipice. However, hurricane „Kyrill” had devastated the area in one of the years before. Thus the slope was now almost completely depleted of trees and uprooted tree trunks lay everywhere. Since the forest floor was not deprived of sunlight anymore, raspberry- and blackberry-tendrils grew wildly. We had to climb over tree trunks all the time and had also to take care not to get caught in the tendrils. Despite the beautiful countryside and the breathtaking view of the mountains, these circumstances turned our ascent into a rather cumbersome endeavor. In between the tree trunks lay steep fields of debris, which threatened to involuntarily transport any not so foot-sure collector downhill in a quite unpleasant way, should he make a misstep.
Eventually we reached the discovery. At that time, the tunneling was already quite advanced and the fluorite band had been followed into the rock for about 5 meters. At first we found specimen with small, light green, sharp-edged crystals. The far better quality was already discernible here – the surface of the crystals wasn’t generally high-gloss but they showed beautiful growth-structures and they had also largely escaped erosion. I was especially fond of the specimen, which were partially covered by stilbite. Most of the pieces are rather structure less plates; due to the parts covered by stilbite, the pieces look far more plastic.
Stephan Weghofer and Reinhold Bacher inside the cleft
One could have been satisfied at that point – since all of our backpacks had been filled tightly. However, we were blessed with luck and found a bubble with extremely color-intensive pieces – and also the size of the crystals became even more impressive. Nonetheless the day was about to end and it was time think about descending.
I just want to briefly address our mode of operation: A team of four offers great advantages. One man is always occupied with the tunneling; another – directly behind the first – transports rough rocks and already secured specimen away. We did this with the help of a bucket and a cable pull, which was operated by the third man. The debris we brought out in this way was not simply dumped down the hill, but carefully stored next to the entrance in order to prevent field damage and not to endanger hikers who might be en route further down the hill. The task of the fourth man was to roughly clean the secured specimen. This has two big advantages: First, specimens of poor quality are already discarded at the mountain, which helps to avoid an unnecessarily heavy baggage on the way down. Second, by way of this pre-selection and cleaning, a first overview of the find is possible, which allows a fair distribution right at the discovery.
Especially the distribution of the find often leads to disagreements among teams of collectors – Not so in our case. All the participants are always careful not to fleece anyone. Everyone is considerate and rather lets somebody else have a particular piece that the other is particularly fond of. It was a great delight for me to work with this team; the comradely atmosphere and the great fairness substantially enhance such an experience.
We took a day off, which I spent at Reinhold’s – once again I visited his exquisite collection, enjoyed his hospitality and the long discussions, which were mainly focused on fluorite. I took pictures of several pieces of his collection, some of which can be seen at my Mindat-gallery.
A little bit relaxed from the exhaustion of the first day we set out again towards the find in the small morning hours of the third day. As promised, we were now at the most successful section of our find. The color of the crystals got increasingly darker, the edge length now reached 4 centimeters and the specimen were almost all in a perfect condition. Especially after a first round of cleaning we were able to see how lucky we were. Each time I had cleaned a particularly beautiful piece I climbed down to my colleagues to show them what they had secured from the rock. All in all we were in a well-nigh boisterous mood. Although the work at the tunneling is especially exhausting (the central gneiss is hard as concrete), none of us wants to pass on the opportunity to regularly take this place. In particular our youngest colleague would hardly let go of hammer and gouge.
Since we all had other obligations the following days, we wanted to fully savor the discovery. Only when the vug with the dark-green fluorites had ended and the space in the cleft had gotten increasingly narrow, did we decide to stop. In the end it wasn’t even possible anymore to remove the bigger rocks from the lower part of the cleft. In order to further work on them we would have had to invest several more days: first breaking them up and then freeing them from the rock. After that one would have had to restart the tunneling and hope for further hollows. Our own needs had been satisfied, the quantity of the find was remarkable and we were more than content. Still, it took us until the late evening hours before we had finished mining, had cleaned the area of the place of discovery so that we could leave it and had divided up the find. We descended under the stars shining on us with our helmet-lamps switched on and reached our cars happily and with heavy backpacks.
uncleaned and fresh from the cleft
A resumption of the works on the cleft would mean considerable investment of material and personnel. Since our demand for specimen has been met, my guess would be that although other collectors will probably try their luck again at this discovery, another tunneling will remain undone. Maybe decades will go by before another team will be engaged at this discovery over a lengthy period of time in order to wrest away more treasures from the mountains. For us it is one more mining-adventure.
Here're some of the best specimens we found: