Modra mining nature trail
Geological structure and evolution
The Little Carpathians are the westernmost core mountains of the Central Western Carpathians. They stretch out in the long (almost 100 km) but relatively narrow (max. about 15 km) horst from southwest to northeast separating the Vienna Basin from the Danube Basin. The fault limit of the Danube basin is known as the Little Carpathians fault and together with other faults in the Little Carpathians it shows some weak but rather frequent seismic activity.
The central part of the Little Carpathians - the core and wider surroundings of Modra - Harmónia is built especially of crystalline rock, which began to settle in the Early Paleozoic (Silurian Geological Period) originally as sandy-clayey sediments (deposits) with an admixture of volcanic material. In the final stages of sedimentation, fine argillaceous rocks settled along with marly limestones. All these sedimentary rocks were later, as a result of orogenic processes, weakly transformed (metamorphosed) into different types of crystalline shale. Volcanic rocks were metamorphosed to amphibolite of different types. About 350 to 340 million years ago (upper Devonian – Lower Carboniferous) the magma of Modra granite massif penetrated into rocks, while the surrounding rocks were metamorphosed into sericite-chlorite phyllites and cherts. Through contact carbonates were transformed into crystalline limestone and calcium-silicate cherts called erlans. Decent occurrence of these erlans is located near Dolinkovský hill, where you can find crystals of grenades in the size of up to 5 millimetres and also diopside, epidote, vesuvian and wollastonite.
Each core mountain range has, in addition to the core, its cover and in the Little Carpathians it consists mainly of Mesozoic sedimentary rocks. The cover is mostly located on the edges of the core, but due to orogenic movements (overlying rocks, faults) it may also be moved to the central part of the mountains. So it is in the area of Modra – Harmónia as well, where the cover is formed by Middle Triassic quartzite with inserts of colourful argillaceous and sandy shale.
Explanatory notes for the geological map
1. fluvial, lithofacial uncategorized loam, sandy loams, loamy sands to gravels of valley floodplains of rivers and streams
2. uncategorised slope sediments
3. colourful argillaceous and sandy shale with inserts of quartz sandstones (Lower Triassic)
4. Lower Triassic quartzite strata (Lúžnanské): quartzite, quartz sandstones, pudding stones, occasionally sandy shale (Scythian)
5. Devín strata: basal polymict arkose breccia, pudding stones and arkose sandstones (Upper Permian)
Paleozoic; Crystalline (Modra massif)
6. double-micaceous granodiorites to granites
7. biotic and muscovite-biotite granodiorites to tonality
Metamorphic rocks; Pernek Group (Silurian - Devonian)
8. marbles and erlans
9. phyllites, metapelites, biotite metasandstones and metawackes with a horizon of graphitic shale
10. phyllites with higher levels of graphitic materials
11. actinolite amphibolites
General explanatory notes
12. anticipated and covered faults
13. found and covered lines of sub-alpine nappe units
14. zones of mylonitisation
15. mining works out of operation
16. quarries out of operation
Modra mining industry is linked to the discovery of precious metals and sulphur, which was derived from pyrite and pyrrhotite. There are no archival references about its beginnings. The first is from the year 1773, when the mining entrepreneur Jozef Entzler conducted an inspection of old mining works in the Little Carpathians, some of which were situated in Modra as well. This suggests that some mining activity had been here already in the past. This is attested by the recently discovered inscription in Bartolomej adit from 1771 and the manner of its digging. An indication could also be the no-longer-existent Gothic church of St. Barbara, who is the patron of miners, which was located in the historical centre of the town. An interesting discovery was also tiles dated from the beginning of the 17th century from the vicinity of some mines. They were found by Pavol Šípka, a local expert on mining, who in the interwar period uncovered several adits with the help of a group of volunteers. More detailed information about the discovery is unavailable; therefore, it cannot be linked to mining activities with certainty.
In the years 1774 - 1800 there were three mining companies registered in the vicinity of the town. The town council did not have positive attitude towards mining business. In 1779 the miners of Michael shaft complained to Hofkammer in charge of mining and coining in Vienna on misunderstandings and irregularities that they had with the town because of the wood required for mining purposes and its price, which was significantly higher than for the rest of the population. The conflict culminated by punishment of the miner Martin Kröpfl for unfounded and insulting accusations of the mining judicial administration in Pezinok and its superior František Kornel Hell.
In 1806 the mining advisor recommended to the Pezinok United Mining Association of Old Town Adits of St. Maria Ann, Theresa, Three Kings, Joseph, Barbara and Cristina a loan or a subsidy to find new sites and carry out gold exploration works in the area of the town. In 1811 F. K. Hell informed of the occurrence of gold in the Trinity adit and lead in the nearby shaft. He recommended more research in the town vicinity. There is a report from 1821 produced by the mine owners Ján Schiller and Samuel Csaplo. It contains a list of adits and shafts in the town vicinity and, among other things, a reference to the currently non-verified occurrence of lead, silver and gold in Joseph adit at Katzenberg. At that time, the activities of miners were only confined to the opening of old adits for several days. The last known document related to the mining industry is from 1838. The aforesaid Pezinok mining association in it asks the Substitution Mining Court for granting an exploration license for discovering gold-bearing and other veins.
Overall there are about 20 underground and countless aboveground mining works within the territory of the town, which is after Pezinok and Pernek the second highest number in western Slovakia. We are not able to identify some adits and shafts mentioned in written sources with mining objects in the terrain and about some of them there are absolutely no references. Even though the mining activities within the town territory were widespread and proceeded in several stages, rare occurrences of the explored ores probably never produced any profits. Intensive mining geological work in progress without geoligical justification in the last third of the 18th century and the first half of the 19th century can be explained by the gold fever in the Little Carpathians.
Stops of Modra mining nature trail
The trail with eight stops is two-way, but for the uninitiated it is appropriate to start from the stop Harmónia water reservoir – adit. To better cope with the trail we recommend hiking boots.
Harmónia water reservoir – adit
The adit is mentioned in 1821. During World War II it was opened and served as a shelter. It was about 40 to 50 metres long. Sometime after the war it was buried. The heap was already at that time being washed away by the Stone Creek and a part of it was used for road construction. At present there are no demonstrable tracks of the adit left nor is it known exactly where it was situated. It is possible that the remains of the mining project were totally smoothed during the construction of the dam or the buildings next to the creek. The adit was dug in granodiorites with closed floes of shale. In the past no traces of mineralisation were found on the rest of the heap.
In the vicinity of the dam on the slope there are a few minor excavations that, however, may not be related to ore mining. The term excavation is understood as a horizontal surface mining work dug into a slope or a rock.
Quarries - underground mines
The first reference of the mines in this area is from 1811. Francis Kornel Hell, at that time a mining advisor, an administrator of mines and an ore processing facility in Kremnica in it informs about the occurrence of lead and gold. A concentrate produced from 1000 cents of ore from Trinity (Dreifaltigkeit) adit contained 2 to 3 lots of gold, which is the equivalent of 0.7 to 1 g of gold per tonne, which would be insufficient for profitable mining. The report also mentions that a shaft was dug from the hill along a lead vein containing 10 to 50 percent of lead. Below these mining works they looked for ores in other adits, but F. K. Hell did not learn of the outcome of the exploration. After a certain time miners left the site because they did not encounter the actual mineralisation. The author of the report recommended research of Modra vicinity because there was supposedly hope for crossing of veins in one of the adits in the lower part of the slope in this area.
In 1821 John Schiller, the owner of Christian adit, and Samuel Csapla, the owner of Joseph adit (both in Modra), proposed digging in the mine rich with lead ore, which was located at that time in the vineyards somewhere in these places. Most likely it is one of the mines mentioned above. The occurrence of lead was also confirmed by ore refinery in Pezinok.
In 1936 mines were opened by the group of Pavel Šípka. Thanks to them we know that the lowermost adit was about 70 metres long, the middle and upper adit, which were connected in arc through a catchment corridor, were also 70 metres long in total. Traces of ore mineralisation were not found there. Currently, the site includes the remains of two adits and one shaft. All, however, are filled up already. In the past described the lowest adit at the bottom of one of the three quarries was probably destroyed or filled up during works in it. There is interesting information from still living elders. According to one of them, in the interwar period, they hauled themselves down into the shaft in a cage using a winch. It has not been discovered yet which of the mentioned adits was Trinity adit. In addition to the mines the anti-tank barrier of the World War II at the southernmost quarry can be considered a monument as well.
Mining works were dug in the area of the contact of granodiorite and crystalline shale, while granodiorite is increasing with depth. In some places granodiorite is directly almost horizontally alternating with shale. The geological structure can be well seen in the walls of abandoned quarries. Currently, the presence of lead and gold in the area is not verified. Based on the paraphrased written report, where it is mentioned, it is not even certain whether the gold accompanied the galena ore (lead sulphide, PbS), as it often does. The occurrence of lead is likely to form an isolated nest or nests without further continuation.
Unused historical roads cut into the terrain are located near the stop.
Three Hills - excavation
The mine is located in the municipal cadastre of Dubová but geographically it belongs to the group of objects that are described on the nearby stops. The excavation was dug in quartzite rocks just as the other mining works on the Three Hills and near the Bear's Rock. Near the mine we can find specularite, which is a variety of ore mineral hematite (iron oxide, Fe2O3).
Three Hills - pinga
Pinga is a vertical surface mining work. The term was adopted from German. The Slovak equivalent is an exploration or mining pit. By size this pinga is one of the largest in the area of Modra.
Three Hills – shallow shaft and adit
A shallow shaft is a vertical near-surface mining work, which was, as opposed to a shaft, dug into a small depth and usually only into a weathered rock. Written sources do not mention a mine. The adit located directly under the shallow shaft was discovered only in 2011. Mining objects were probably linked, but without removing the heaps it can be proved only by geophysical methods. In this area as well as at nearby stops, in addition to the objects described above, there are also several small pingas and excavations. The nerby Bear's Rock provides limited views and is a popular climbing site.
Bear's Rock – Bartolomej adit
The only known reference of this mine is on the list of mines from 1821. On the cadastral map of the town of 1851 in the area of the Bear's Rock, there is the name of Christine Stolln (Cristina adit) recorded, but without a precise location we cannot establish with certainty that this mining work is identical with Bartolomej adit. Inscription in the mine from 1771 at a considerable distance from the entrance and the archaic method of digging proves that the mining work was created in several stages and perhaps even before the 17th century. Besides this inscription there are also other epigraphic monuments in the mine from the 19th and 20th century. During World War II, after the suppression of the Slovak National Uprising, the Bear's Rock was one of the places where 11th brigade of General Štefánik of 2nd Stalin's Partisan Brigade stayed. It is possible that the partisans used the underground spaces as shelters.
Some of the adits of the mine were dug by the method of manual hewing and got the name "hews". In the front part of the corridor (hall) in the direction of the digging using chisel and hammer they hewed vertical and horizontal grooves spaced apart. The resulting bumps were then removed using a hammer. Such an extremely strenuous work allowed going into hard rock just a few tens of meters of the corridor per year.
The mine has two floors and the total length of the corridors is nearly 400 metres. In the vicinity of Modra it is the largest mining project and in western Slovakia it ranks among the longest preserved related to the exploration and mining of precious metals. Right next to the heap the remains of some building, maybe for storing tools or explosives, as was the custom in larger mines, were found.
The adit was dug directly into large weathered quartzite. There were no traces of mineralisation in it; therefore, the scope of work is remarkable. The position of quartzite with minor quartz veins was considered by miners as an appropriate environment for the occurrence of gold. And the presence of specularite, which creates clumps of nice shiny silver crystals, could have lead miners to misinterpret it for galena and thus brought the assumption that there may have also been present other commercial ore minerals including gold. Specularite, however, occurs relatively abundantly in quartzite as its usual addition and does not have anything to do with potential mineralisation.
Please note that entry into the mining work is prohibited!
Bear's Rock – adit
It is possible that this mine is John (Johan) adit, which is mentioned in the list of mines from 1821 next to Bartholomej adit. Considering the small heap, its length did not exceed approximately 10 metres. The destruction of the entrance to the adit looks like an excavation, which can be confused with the object of this size.
Lower Bear's Rock - Hidden excavation
Morphologically it is an interesting mining work discovered only in 2010, which is implied by its name as well. The farthest point of the dug space is located approximately 10 metres from the edge of the rock; therefore, it is not completely accurate to classify this object as an excavation, since the ceiling of the mine at this point creates the feeling of being underground. A barely noticeable heap is located directly in front of the excavated area. A part of the excavated rock was apparently stored in the mine. In the Little Carpathians there is no mining object forming an overhang. The rock is also used for climbing, but it is relatively easy to get to its peak, which does not provide a distant view, even without climbing gear.
Next to the rock there is one significant pinga. The second one was probably destroyed by the road.
The mine is recorded in the list of adits and shafts from 1821. It has retained the entrance and is passable in all length, approximately 40 metres. In the underground the corridor splits near approximately 3-metre shallow shaft. At the end of the left corridor a shallow pit is dug out. Manual digging of corridors, the shallow shaft and the pit may be evidence that the mine was founded before 1627.
The adit, following a minor fault, was dug into a protruding cliff consisting of quartzite and disintegrating quartz pudding stones. There is no visible mineralisation in it.
According to the census of 1821 the mine, at that time in the ownership of Samuel Csapla, contained gold-silver-lead ore. The adit later received the name Christian.
Parts of the adit were still accessible until 1950's. In one of its branches, there was a steep inclined slope of about 30 metres long. Allegedly about 80-metre long corridor was inaccessible. Currently, the entrance to the mine is inaccessibly covered.
The mining work was dug in quartzite and siliceous, sandy disintegrating pudding stones. In the top wall of quartzite and pudding stones the adit caught clay-micaceous shale and in the basement granitoids. Geological survey in 1950's did not confirm gold-silver-lead mineralisation. In the underground and on heaps only rare occurrence of specularite was found.