Karst marbles

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As Karst marbles are natural stones north of the region, east and south of Trieste called. These rocks are extracted from the Aurisina (Slovenian: Nabrežina), Monrupino and Sežana deposits . Most of them are bioclastic limestones and not marbles in the petrographic sense.

General construction newspaper 1876

Explanation of terms

Instead of the common term “karst marbles”, “karst limestone” is occasionally used. Both terms are misleading because natural stones are also mined in other karst regions of the world.

The term "karst marbles" for the group of building and decorative stones from the area around Trieste and on Istria solidified in the era of the Austro-Hungarian monarchy , when these stones were extremely popular for the construction of public and private buildings. This applies particularly to the 19th and early 20th centuries. This collective term was transferred relatively quickly to the competing limestones from the Istrian karst areas. In this context, not only the specific regions of origin (Trieste Karst or Istrian Karst) of various karst limestone are blurred in contemporary architecture, but also individual trade names of successful varieties are used by completely different quarries (for example San Stefano limestone , Grisignana marble or Giallo d ' Istria ) in the former economic boom with karst rocks seemingly arbitrarily used. It is often a difficult task for skilled workers to clearly determine the exact origin of the varieties installed on historical buildings.

History of mining

It can be assumed that so-called scrubs and sinkholes , i.e. natural karst phenomena in the area, are the starting point for the extraction of the simple building blocks required.

The use of limestone deposits near Trieste for the extraction of ashlar can be traced back to pre-Roman times. Former village castles (hilltop castles) above Trieste were built from the karst limestone and are for the period around 1500 BC. Demonstrable.

Church tower in Gorjansko, Slovenia
Defense tower in Lokev (Slovenia)

In the Roman era, stone quarrying was already established in the Tergester (Trieste) area and served the material requirements in construction and sculpture. Buildings of the Capitol in Tergeste, the basilica and the only fragmentary amphitheater were built with Aurisina limestone.

In Aquileia (founded in 181 BC), contrary to earlier assumptions, there are only a few and late architectural parts from the fractures in the vicinity of Aurisina. The oldest stone remains, on the other hand, are sandstone from the Muggia region and the port facilities of this ancient site were built by the Romans from saltwater-resistant Istrian limestone. The material of an Ionic capital has been identified as karst limestone from Santa Croce (Antico Timavo) near Trieste (Tergeste).

South of Aquileia, the Via Gemina ensured the necessary mobility for trade and the military to Pula and, further south, the Via Flavia to Dalmatia . The road system facilitated the transport of raw stones and finished components to neighboring areas or to nearby ports. The high and steep bank of the Adriatic Sea did not allow a safe road layout. In the region under consideration here, the Roman road ran on the karst areas above today's city of Trieste to Istria. Today we find the most important mining areas of Triester karst limestone on both sides of this street.

In the sculpture of Venice in the 8th to 10th centuries the karst limestone from the Aurisina mining area played a leading role. It should be noted that many quarries between the Trieste region and southern Istria supplied building material for Venice and other northern Italian cities . The relatively easy transport across the Adriatic Sea made it much easier to use.

From the late Middle Ages and the Renaissance there are few testimonies and references to stone quarrying near Trieste. A revival of the quarries can only be recorded in the 18th century. When Trieste was declared a free port in 1719 , building activity increased.

In modern times the karst limestone got its big chance from the Viennese architect Hans Christian Hansen . Hansen was considered one of the most unusual connoisseurs of building stone among architects of his time. He acquired much of his knowledge after studying (until 1828) during his stays in Rome , Naples , Sicily and Athens . Among other things, he designed the university building in the Greek metropolis (from 1839). As an educated personality, Hansen also took part in archaeological work in Greece.

The wealth of experience he gained brought him the order from Austro-Hungarian Lloyd to plan the facilities of the Trieste port area as the gateway to the Mediterranean, which is particularly important for Austria-Hungary. Before that, he traveled to various European port cities over a period of three years to get to know their structure and functionality better.

Finally, Hansen decided to use Aurisina limestone entirely for the construction of the dry docks and the functional buildings. This gave the stone quarries located in the region a great boost. The contemporary coverage of the construction of the arsenal in Trieste attracted the greatest attention in Vienna and other cities. The stone from the Trieste Karst experienced a growing demand. In architectural circles at that time, one of the rules that applied was that buildings should be built to last. This had direct consequences for the carefully considered use of materials for facades, stairs and floors. The low water absorption capacity and other rock-physical properties of numerous types of karst limestone meet exactly those expectations for "eternity".

simple stone carving in Skopo, Slovenia; typical limestone element in the region's vineyards

The unusual attention paid to the stone from the former Austro-Hungarian crown land, the coastal region, increased when a large natural stone presentation by the Imperial Geological Institute was on view at the Vienna World Exhibition in 1873 .

geology

Section of the geological map of the Istrian coastal region by Guido Stache, 1864

stratigraphy

The Lausanne professor Charles Adolph de Morlot created the first geological map of the Karst region and Istria in 1848. Comprehensive and coherent information about the geological structure of the Trieste Karst was only created with the field work by Guido Stache from 1858 to 1859 and 1877 and in the period from 1886 to 1891. In a smaller area of ​​the Karst, the area around Sežana, geological mapping work began in 1895 by Franz Kossmat .

The karst landscape of Trieste belongs to the chalk system. Only two assignments are relevant for stone quarrying in the modern era.
The Aurisina / Santa Croce deposit is assigned to the Senon ( Upper Cretaceous ). In regional geology , the Upper Nabresina stage is also used.

The limestones of the Monrupino deposit come from the transition phase between Cenoman and Turon (both Upper Cretaceous ).

Mineral composition

The main component for the varieties from the Aurisina / Santa Croce, Monrupino and Lipica mining areas is calcium carbonate, with a proportion of 96.6% to 99.5% depending on the variety. The stones from the Monrupino area and the Slivia breccia have slightly higher proportions of magnesium carbonate . Iron compounds and other accessory ingredients are about 0.1% or less. There are no calcite veins and noticeable cavities are very rare (for the Fior di Mare variety , Monrupino mining area)

Rock description

The particularly valued property of many types of stone from the Trieste Karst is the low number of pores and thus the very low water absorption capacity. This rock-physical feature gives them a high degree of frost resistance, which is why they were often used on facades. Their values ​​of water absorption are between 0.90% ( Repen Classico ) and 13% ( Roman Stone ). The high density of most karst marbles enables excellent polishing.

With regard to the color palette, the stone of the Trieste Karst shows shades of light beige to golden beige for the main varieties from the Aurisina and Santa Croce mining area and gray beige to light gray for the varieties from the Monrupino mining area. To the south of it, at Sežana and Lipica, light beige to beige-gray rocks are extracted again. Some smaller mining sites further to the east, for example from Kopriva (historical), show a darker appearance due to the large gray-brown fossil shell pieces they contain.

Many types of stone from the Istrian karst area are tinted golden beige or light beige.

If you look at the structures, two basic types can be identified. One group is formed by the bioclastic sediments with predominant fragments of fossil shell remains ( lamellar branches , rudists , bryozoa , ostracods ). These bio-critical limestones are typical of Aurisina, Santa Croce and Lipica.

The Monrupino deposit consists mainly of reef limestone ( intraclastic biomicrites) and represents the second basic type. Small and large debris from former coral reefs are enclosed with individual fossils in a very fine-grained limestone mass . Lamellibranchies, foraminifera and echinid radiolites are found on fossils , most of which catch the observer's eye due to their dark brown color.

The group of karst marbles is a Kalkbrekzie ( Cava Slivia ) and several smaller deposits of aragonite sintered lime ( Stalattite enriched) on Italian and Slovenian side.

For a complete knowledge of the region, the very dark to brown-black limestone from mining sites on Slovenian territory between Komen and Tomaj should also be mentioned. They are known from the history of decorative stones under the names Nero del Carso , Paragone or Nero Nube and are no longer extracted today.

  • Limestone Aurisina Romana (Italy)

  • Limestone Aurisina Granitello (Italy)

  • Limestone Repen Classico (Italy)

  • Limestone Kopriva (Slovenia)

Dismantling

Kornárija limestone quarry in northern Istria

The usual form of stone quarrying in the Trieste Karst is the broken manhole. The only slightly undulating landscape and in some cases used sinkholes as well as the vertical dimension of the deposit produce shaft-shaped quarries. At those places where several manhole breaks merge with each other, a rift valley occurs (for example in the area of ​​Cava romana). Lateral developments of the deposit (Lehnenbruch) are less common in the sloping terrain. They allow for easier removal of raw blocks (for example Cava Petrovizza).

In individual cases, stone was and is extracted underground. The most famous example of this region is the "Cava romana" quarry in Aurisina. In the western wall of the area, which is still in use today, open mining rooms with several supporting pillars made of limestone have been preserved from antiquity. Modern dismantling takes place above ground using bench construction .

In the Lipica deposit, modern limestone extraction is also carried out in the underground extraction operation with scrapers .

The stone in the Croatian karst areas are mostly obtained by building a bench. Many formerly common mining sites are now closed. Some were already of great importance in the Roman era, for example the Valtura quarry for buildings in Pula .

Application forms

Sculpture
Facade masonry
Balustrades and parapets
Staircases
Wells
Floor coverings
Heavy masonry (e.g. docks)
Bridge structures
Graves
monuments

Application examples

Architecture of the Trieste Governor's Palace
Facade made of Aurisina limestone
Monument near Hněvčeves / CZ

Italy :

Austria :

Czech Republic :

Hungary :

Cross-national examples :

  • Railway line of the southern section Trieste-Ljubljana: railway buildings and bridges

Other places of use :

  • Buildings in Ljubljana, Maribor, Debrecen, Arad, Temesvar, Osijek, Belgrade, Bucharest, Alexandria, Port Said, Cairo etc. a.

Architects used Trieste limestones (selection)

Commercial grades

The trade names have been subject to fluctuating influences over the past 200 years and are sometimes irritatingly changeable. The closer relationships were shaped by sales-oriented, everyday language and regional-specific peculiarities. In addition, direct historical language influences from Italian, Slovenian and German exercise the name. A detailed representation of changing and corresponding trade names of all stone of the Trieste and Istrian Karst cannot be given in this context. The following are only the most important names of varieties, most of which are still comprehensible or in use today:

From the Trieste area

Aurisina Roman Stone (Aurisina Romana)
Aurisina Granitello
Aurisina Fiorito
Repen Classico
Repen Fiorito
Repen Tabor
Monrupino
Fior di Mare

From Istria

Canfanaro
Giallo d'Istria
Grisignana marble ( Grožnjan )
Marzana
Merlera
Orsera

literature

  • Aleš Brecelj / Zvonko Legiša / Ivan Vogrič: Nabrežinski kamnolomi. Trst [Trieste] 1989
  • Franco Cucchi / Santo Gerdol et al .: The natural stone from the Trieste Karst. Trieste (Camera di Commercio Industria Artigianato e Agricoltura) 1989
  • Felix Karrer: Guide through the building material collection of the Imperial and Royal Natural History Court Museum. Vienna 1892
  • Franz Kossmat: Special geological map of the kingdoms and countries of the Austro-Hungarian monarchy represented in the Reichsrat: Sheet Haidenschaft and Adelsberg Zone 22, Col X. (1: 75,000). Vienna (publishing house of the Imperial Geological Institute) 1905
  • Richard Schubert: Balkan Peninsula: A. The coastal countries of Austria-Hungary. (in: Handbuch der Regionalen Geologie), Heidelberg (Carl Winters University Bookstore) 1914
  • Robert Seemann / Herbert Summesberger: Wiener Steinwanderwege: The geology of the big city. Vienna (Verlag Christian Brandstätter) 1998, ISBN 3-85447-787-2
  • Guido Stache: Geological landscape of the Istrian coastal land. Vienna 1864
  • Guido Stache: Addendum to the special geological map of the kingdoms and countries of the Austro-Hungarian monarchy represented in the Reichsrat: Sheet Gorizia and Gradisca Zone 22, Col IX. (1: 75,000). Vienna (Verlag der Geologische Staatsanstalt) 1920
  • Guido Stache: Addendum to the special geological map of the kingdoms and countries of the Austro-Hungarian monarchy represented in the Imperial Council: Sheet Trieste Zone 23, Col IX. (1: 75,000). Vienna (Verlag der Geologische Staatsanstalt) 1920

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