The quarry of grey and pinkish multi-coloured marble, Lesno Brdo, is situated in Lesno Brdo, near Ljubljana. It has been extracted for many centuries and is thus a prominent feature of the Slovenian cultural heritage.
Taking a walk around Slovenian towns, one can observe it as a constituent of the most important cultural memorial structures, such as the Fountain of the Three Carniolan Rivers (Robba Fountain, by Francesco Robba) at Town Square in Ljubljana.
|Quarry location||Slovenia / Lesno Brdo|
|Compressive strength||85 MPa|
|Compressive strength after freezing||81 MPa|
|Bending strength||8,4 MPa|
|Coefficient of thermal expansion||0,008 mm/m°c|
|Modulus of elasticity||713 MPa|
|Slip resistance (polished)||27,2 units|
|Slip resistance (cut)||60 units|
Geotectonicly, the area is part of the Outer Dinaric Alps. The area where Lesno Brdo lies, is part of a larger geotectonic unit, Blegoš-Vrhnika range. The quarry and its surrounding areas are mainly composed of carbonate stone (limestone and dolomite) that formed in the Triassic period, over 230 million years ago. Its southern edge is overrun by watercourse deposits and alluviums from Ljubljana marshes. To the east it is in an overthrust contact with sedimentary stone from the Permian-Carboniferous period, which geotectonicly belong to the Škofja Loka-Trnovo nappe.
The Lesno Brdo quarry includes two stratigraphic elements - Cordevolian limestone and Julian clastites. Cordevolian limestone represents a productive series that is further represented by two lithological elements in the quarry:
Pinkish and pink-grey limestone
Dark greyish limestone.
Limestone comes in the shape of a NW–SE oriented lens. The maximum surface width of the lens is 100m, 80m in the quarry, and its length is around 350m. The age of the limestone was determined with regard to the superposition of the layers and with the help of numerous fossils found there. Reef limestone mostly consists of sponges, bound together by cyanobacterial crusts. Most sponges are non-articulated, but there is also one species of an articulated type, Solenolmia manon. The othere constituents forming the reef are corals, which are also almost always coated with spongiostromatic crusts. The multi-coloured limestone includes smaller amounts of corals (Margarphyllia capitata and Volzeia sublaevis). Limestone further consists of bivalvia, gastropoda shell and sea urchin remnants.
In the NE direction, the limestone keeps its main lithological characteristics, although it slowly loses its reddish hue and colourfulness. First it gradually becomes a more monotone, greyish to slightly pinkish limestone, and then dark grey. The border between the multi-colour and dark grey limestone is difficult to determine, as both kinds are interwoven and repeat periodically in a wide area.
On the south side of the Lesno Brdo quarry, the productive series borders on the lower Julian layers. These layers are discordantly deposited onto the Cordevolian reef limestone in a wide area. At the extraction site area, the Julian layers are mostly represented by reddish and partly yellowish and grey-green flysch as well as fine-grained sandstone.
The border between Julian sandstone and flysch, and between Cordevolian reef limestone is erosively discordant.
There is very little deposited soil on the surface layer of the quarry, as its thickness ranges from several cms to over 2m in karst pockets. The deposited soil is represented mostly by rendzina or terra rosa, which is mixed with limestone parts. This sediment, with mostly clay and sand fraction of particles, has a characteristic reddish colour.