2017, Blue Fluorite, Weisseck
There is a locality at the Weisseck that has so far received little attention in the literature. It produces blue fluorite of exceptional color and quality, in some cases with remarkable edge lengths. In locality descriptions, this site has often been referred to as “Weisseck East Slope.” This designation is incorrect, however, as the occurrence is actually situated on the southern side of the mountain.
Collecting at this site is extremely dangerous: the limestone has been fractured in all directions by frost action, and large blocks of rock are only loosely held together. Mineral collectors must crawl beneath the rocks and proceed with extreme caution to prevent this unstable structure from collapsing. With a bit of luck, however, one may be rewarded with an outstanding fluorite distinguished by its fantastic color and high transparency.
This locality was discovered in the 1990s by a collector from the Lungau region. A surface find first drew his attention to the site. Further fluorites were uncovered during shallow digging, which triggered a larger excavation campaign. A group of collectors from Lungau worked intensively at this new locality for several days and made some remarkable finds.
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A group of collectors from Lungau at the newly discovered locality
One of these collectors was Walter Petzelberger, from whom I obtained several of the fluorites presented in this report. Even at that time, the collectors faced major problems with the instability of the rock and were constantly exposed to the danger of unexpected rockfall or collapse of the excavation.
Busy activity and work at the locality
Makeshift support using relatively thin wooden poles
As the collectors were standing on a collapsed fissure, they had to dig vertically downward to reach the sought-after fluorites. Among the debris and rock fragments, they repeatedly found fine specimens. The deeper they dug, the larger and better the crystals became. They attempted to counter the instability by installing supports. Thin wooden poles were carried up to the Weisseck to brace the overhanging, sometimes very large rock blocks. Entering the pit and digging for fluorite was an extremely risky undertaking—one never knew if or when the excavation would collapse. Eventually, the pit became large enough for two collectors to work in simultaneously. The debris was passed upward in buckets and emptied by the collectors standing outside. When time allowed, the recovered specimens were already packed outside. One collector always remained directly at the locality, carefully observing the rock in order to warn his colleagues working in the pit in case of danger.
Directly in front of the locality, descending steeply downward
It was only a matter of time before a collapse would occur. However, the finds continued to improve, and so the work went on. Two collectors were in the pit and had just discovered a pocket with fine fluorites in the debris when a call came from outside: “Get out immediately!” At first, they did not react, being completely focused on the fluorites. The call was repeated, this time much more urgently. Only then did they respond. Now the collectors began to climb out. The trickling intensified. One collector was already outside, while the second was just emerging. Hands were stretched out toward him; he grasped them and was pulled out of the pit with a strong jerk. Almost simultaneously, everything collapsed with a dull roar. The collectors had escaped a serious accident by a hair’s breadth. From that day on, the locality remained untouched for several years.
Although untouched, it was not forgotten—too beautiful were the blue fluorites from this site displayed in collections to avoid thinking about how this locality might one day be safely worked again.
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Outstanding fluorite specimen with excellent transparency and an edge length of 4.4 cm, 11.2 × 7.5 × 5.2 cm
From 2008 onward, work resumed at this locality. The composition of the collecting team changed several times, but it consisted predominantly of collectors from the Lungau region. The first years were very laborious: large amounts of debris had to be removed, yet only few fluorites were found, as work initially focused on areas that had already been excavated previously. In addition, the excavation repeatedly collapsed. Especially after thunderstorms or prolonged rainfall, the previously dry clay softened, causing the excavation to become unstable and cave in. This usually happened in the collectors’ absence. They then had to spend hours removing debris to reach the point where they had last stopped working. At that time, I was already heavily involved with the Eiskluft locality and therefore did not experience these difficulties directly.
From October 2013 onward, Anton Baier also worked at this site. He fundamentally changed the working method and began timbering the shaft. This significantly increased stability and allowed deeper excavation. In the following years, this technique was consistently applied. Enormous amounts of debris were removed, and the effort was eventually rewarded with very fine finds.
Through Anton’s initiative, I was invited to participate in July 2017. I was very pleased with this opportunity, as I had always been particularly fond of these fluorites. At first, however, the invitation meant hard labor, as the shaft had once again collapsed and a large volume of debris had to be cleared.
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Toni working in the shaft; the debris always had to be hauled up with great effort
It took many hours to reach a depth of nearly four meters. From this level onward, the debris became productive, and excavation had to proceed with increased caution.
Toni with two freshly recovered fluorites
Another cabinet specimen!
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Collapsed excavation site after a rainy day
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Freshly cleaned specimen
The fluorites from this locality are particularly striking because of their blue color, which ranges from deep blue and light blue to greenish blue and violet. Some fluorites show an internal gray coating that does not transmit light, causing some specimens to appear completely gray. Others display this gray coating on only one or two cube faces, while the remaining areas are transparent. The most desirable specimens are those that are completely transparent. All fluorites are cubic in habit and reach edge lengths of up to 8 cm. The crystal surfaces display a fine quadratic structure, which in many specimens is no longer visible due to water etching. In protected areas, fluorites with very good surface quality could be recovered. Larger crystals often show pronounced stepped growth along the edges. Some specimens also display multiple growth zoning. The finds consist of detached individual crystals, floater specimens, or matrix specimens. The matrix is either limestone, or the crystals are grown on thin quartz plates. Associated minerals are mainly small, light-colored calcite crystals and small quartz crystals of about 1 mm in size. No other associated minerals are known to me.
Single transparent cube with an edge length of 6.3 cm, 6.3 × 5.7 × 4.8 cm
Floater specimen with two dominant crystals up to 4.2 cm and calcite, 11.3 × 7 × 6.5 cm
Transparent fluorites up to 6.7 cm edge length, 17 × 12 × 7.3 cm
Fluorites up to 3.5 cm on limestone matrix, 18 × 13 × 11.5 cm
Lustrous fluorites with 2 cm edge length and growth zoning, grown on thin quartz plates, 19 × 12 × 10 cm
Fluorites with good surface quality, crystallized on thin quartz plates, 9.8 × 9.8 × 4.5 cm