The Calcare di Aurisina (Also known as Aurisina Formation, “Formazione di Monrupino”, Trieste Karst Limestone formation, “Repen formation”, “Sežana formation” and “Lipiza formation”) is a Mesozoic geologic formation in Italy and Slovenia. This limestones are found in the Trieste area and are of Late Cretaceous (Santonian-Campanian) age, being a local record of Carbonate platform limestones, historically quarried by cutting large blocks using steel wire, what has allowed more access to them, as numerous quarries allow excellent exposure. Due to being cut into large blocks and slabs, that usually end stored near the quarries, detailed, three-dimensional study of the rock's composition and fossils can be easily done.

Characteristics

The Aurisina limestone has usually a light grey background, sometimes appearing hazelnut in color. It is known for its high purity, compactness, and uniformity. The quarries where it is extracted consist of thick, solid layers of stone. Different varieties of Aurisina marble are distinguished by shades of grey and the distribution, size, and orientation of the organic remains within the stone. Well-known varieties include Aurisina Fiorita, Aurisina Lumachella, Aurisina Chiara, and Roman Stone, among others. Aurisina marble's chemical composition and physical properties make it ideal for use in architecture, both for structural and decorative purposes, as well as in statues and monuments. The stone is valued for its durability and aesthetic appeal in various applications.

Historical Importance

The Aurisina Limestone has been used since the Roman Republic. Evidence from ancient monuments in Aquileia, a Roman colony founded in 181 BC, suggests that quarrying began in the 1st century BC and continued until the 5th century AD. The stone was widely used in Aquileia for architectural elements, statues, and funerary monuments. The nearby city of Tergeste (modern Trieste) also made extensive use of Aurisina Limestone for public buildings and sculptures. Its use spread across northern Italy, with artifacts found as far as Pavia. In the post-Roman period, Aurisina marble was notably used in the Mausoleum of Theodoric in Ravenna, built around 520 AD. However, its use declined during the medieval and Baroque periods. In Venice, it was replaced by Istrian stone, but in Trieste, it saw a revival in the 18th century as the city grew following the establishment of the free port by Emperor Charles VI. Notable examples of its use in Trieste include Palazzo Pitteri (1780), the Stock Exchange (1802), and the renovation of the Greek Orthodox Church of San Nicolò dei Greci (1819). Aurisina Limestone 's "golden age" came under the Austro-Hungarian Empire, particularly after the completion of the Southern Railway, connecting Trieste to Vienna. The stone was used in major projects throughout the empire, including the Parliament and Hofburg in Vienna, the State Opera in Budapest, and many buildings in cities like Graz, Munich, and Ljubljana. By 1890, the industry employed over 3,000 workers. After Trieste's annexation to Italy in 1918, Aurisina Limestone was used in large-scale projects like the Military Shrine of Redipuglia and Milan's Central Station, where 38,000 tons were utilized. During this period, the marble also reached international markets, being used in Egypt and the United States. In the post-war era, Aurisina Limestone continued to be popular in foreign markets, with notable projects including the Atlanta subway in the U.S., Berlin airport, and La Défense in Paris. In 1989, it was used for Milan Metro's Line 3. More recently, it has featured in prestigious architectural projects, such as Milan's Citylife Shopping District designed by Zaha Hadid and Turin's Lavazza headquarters. Internationally, it is used in projects across Europe, Asia, Australia, and the U.S.

Paleoenvironment

The formation is characterized by lagoonal facies with episodes of higher energy and rare bivalve patch reefs, such as Chondrodonta and Rudists, which are found throughout the entire unit. The lower section, referred to as the "Zolla member" consists of bivalve-rich limestone, including rudists and Chondrodonta, as well as foraminiferal limestone, often interbedded with dolomitized dark wackestones. In the upper part of this member, pelagic limestone with Pythonella fossils is present. The main body of the Aurisina Limestone is characterized by peritidal carbonates, with some dark laminated facies, dominated by rudists, benthic foraminifera, cyanobacteria (Decastronema), and algae (Thaumatoporella). The Paleoenvironment of this unit is accepted to be a succession of emerged and shallow marine carbonate platform settings, including inner lagoons, high-energy shoals, tidal channels, and rudist accumulations The complex dolomitization and silicification in the region may be linked to a Monsoon climate with alternating wet and dry periods. Comparable dolomitization occurs across the Adriatic Platform, particularly in the Middle-Lower Cenomanian. The Villaggio del Pescatore site revelated bauxite and coal levels in the surrounding sediment indicate a humid climate. This karst region directed most water underground, limiting surface streams. Fossils of Hadrosaurs were found in a 10-meter layer of laminated limestone within a karst depression, unlike other hadrosauroids typically preserved in fluvial or marine deposits. The site also contains remains of small crocodyliforms, fish, and crustaceans, which suggest fluctuating anoxic conditions that preserved the fossils. This depression likely functioned as a cenote, attracting animals seeking water, where some may have drowned and remained preserved in low-oxygen conditions at the sinkhole's base.

Biota

Bivalves

Cephalopoda

Crustaceans

Cnidaria

Chondrichthyes

Bony Fish

Crocodiles

Pterosaurs

Dinosaurs

Flora

Palynology of the Villaggio del Pescatore section has been studied, dominated by a few gymnosperms and several angiospermous pollen types.

Image Gallery

Footnotes