Natural stone, Limestone
The white stone from Brač Island, also known as 'Veselje unito / fiorito', derives its name from an ancient quarry in Veselje Bay. The high quality of stone made this quarry the source of choice for renowned local builders. Over time, three additional quarries emerged in the vicinity - Sivac, Barbakan, and Punta. Additionally, the island boasts gray-white dolomitized limestone ('Sivac') among its resources.
- Name of Material in the local and Latin language
- Kamen (Lat. Calx)
- Type of Material
- Natural stone of sedimentary origin
- Commonly Found Locations
- Upper Cretaceous deposits of the Adriatic carbonate platform; Pučišća formation on the island of Brač with distinct stones 'Rasotica', 'Veselje', and 'Sivac'
- Major Industrial Producers or Suppliers
- JADRANKAMEN d.o.o. - industry of Adriatic stone and marble; Exploitation field in the bay of Veselje - quarries Punta, Barbakan, and Sivac
- Colour
- Limestone is composed of calcite, a petrogenic mineral that can be white or coloured. The colour of limestone varies from pure white through yellow, red, grey to dark brown bituminous limestone.
- Hardness
- Calcite is a petrogenic mineral with a relative hardness of 3 on the Mohs scale of hardness (the scale ranges from 1 to 10). All rocks in the Earth's crust naturally contain quarry or quarrying moisture. The moisture content of the stone affects its softness and thus the ease of processing. By losing moisture, the stone achieves resistance and better physical-mechanical properties.
- Melting/Boiling Point
- Quicklime is obtained by roasting limestone in kilns at temperatures exceeding 800°C. Using a solution of slaked lime, stone roofs of houses are whitened and disinfected, allowing water that flows over the roof into cisterns to be purified and immediately ready for use.
- Solubility
- When stone comes into contact with salt and acid rain, it mechanically fractures and chemically dissolves. The deterioration is evident through exfoliation (flaking, peeling, and scaling) and efflorescence (the crystallization of salts on the stone, appearing as white powder).
- Structure
- Limestone has an organogenic structure that formed through the deposition of carbonate skeletons of various shells.
- Chemical Composition
- Limestones are carbonate rocks with a mineral content of calcite greater than 50%. Pure limestones contain more than 90% calcite (CaCO3). Limestones with a lower content of calcite and an increased content of dolomite (CaMg(CO3)2) are called dolomitic limestones.
- Industrial and Crafts Applications
- Architectural and construction stone consists of regular blocks of standard dimensions used to produce stone slabs for horizontal and vertical cladding, serving as decorative, protective, and functional elements in building structures. Stone is also utilized as a structural component, such as in arches, vaults, domes, roofs, cornices, stone gutters, staircases, and balustrades. Technical construction stone (crushed, broken, and ground stone) refers to finely crushed stone material with a loose aggregate structure (granules), applied for various purposes in construction or as raw material for industry. In addition to construction, Brač stone is used in memorial architecture and sculpture, as well as for crafting souvenirs and jewelry.
- Historical or Cultural Uses
- Dry stone walls, stone huts, cairns, cisterns, and ponds, as well as 'pjoveri' (small stone shelters). This tradition continues to the present day, showcasing the enduring legacy of building techniques on the rocky terrain. Dry stone architecture bears witness to the struggle of farmers with stone and meager soil. By constructing cisterns, ponds, and 'pjoveri', people found refuge from drought, while stone huts served as shelters for shepherds in the fields. The love between people and stone is perhaps best reflected in the fact that the local population regards stone as a precious resource, akin to their harvest, and thus they 'harvest' stone with care.
- Environmental Impact
- The selection of areas for mining architectural and construction stone relies on quality assessments of the stone, available quantities, and potential quarry expansion. Quarrying brings about substantial alterations to the landscape and ecosystem, leading to soil erosion, vegetation loss, and contamination of surface and groundwater. Dust, gasses, waste, and overburden further degrade air quality and human health. Consequently, surface quarries reshape the visual character of regions. Exploitation is restricted near urban areas, cultural landmarks, national parks, roads, power lines, and water sources. Massive stone exploitation leads to a depletion of stone reserves and the closure of quarries. When the stone is depleted from its deposit, it's necessary to rehabilitate the quarry properly. Typically, stable terraces and slopes are formed from quarry levels and then planted with suitable native vegetation. This process transforms the dead rock material on the plateau and slopes of the surface mine into soil suitable for the life of plant and animal organisms. This is known as biological quarry rehabilitation. The transformation of quarries is particularly attractive. It's popular to shape quarry spaces in an amphitheater style for various events such as fairs, performances, exhibitions, concerts, weddings, and more. Quarries located below sea level can be used for building marinas, hotels, shipyards, climbing facilities, and similar purposes. However, quarry rehabilitation is rarely practiced in Croatia. A good example is the Vinkuran Quarry (Cava Romana) located a few kilometers from Pula, where festivals, workshops, and concerts are held.
- Extraction Methods
- Stone blocks are extracted by diamond wire saws and chain saws. After separation from the parent rock, the blocks are lowered onto the working platform by hydraulic or pneumatic cushions.
- Processing Techniques
- After lowering the primary block is sawn into commercial-size blocks. Grinding and polishing of marble and limestone are performed after cutting and trimming, once the product has obtained its final shape and dimensions.
- Interesting Facts or Historical Anecdotes
- In the past, the stone was broken by using iron wedges. Workers would line up next to each other and, upon a signal 'Hop!' or 'Jan!', they would strike in unison until the rock separated. When determining the quality of a stone block, the speed of sound transmission through the stone is important. Although neglected today, this method was commonly used by old stone masters who would strike the surface of the block with a hammer or mallet while carefully listening to detect its strength, porosity, and the presence of veins that could cause the stone to break.
- Relevant Organizations, Associations, Producers
- The Stonemasonry School in Pučišća has fostered a longstanding partnership with the trading company Jadrankamen, which supplies stone blocks for teaching purposes. This collaboration extends to the organization of the international Symposium on Quarrying, Processing, Installation, and Stone Restoration. Additionally, the publication of the magazine 'Stonemasonry and Architecture' serves as a platform for interdisciplinary studies of architecture and the utilization of architectural stone. The school is well-known among both local and European vocational schools, attracting students from Croatia and beyond. It's a key part of promoting tourism on Brač and is involved in projects like WinStone (which helps women join the stone industry) and Vocations in Stone. In collaboration with Oris House of Architecture, it organizes the Tripun Bokanić Award competition, which recognizes exceptional achievements in the field of stone shaping. Young stonemasons, united through the student cooperative 'Kapitel', participate in numerous projects.
Decorative white and gray stone is a distinctive feature of the Brač Island. Although of Upper Cretaceous limestone origin, it is often referred to as marble because it can be polished to a high shine. Local limestone appears in about ten variations, ranging from pure white to dark brown bituminous limestone (‘Rasotica’).
‘Rasotica’ is characterized by abundant large, white rudists in a brown base. As the rudists are elongated fossilized shells (‘horns’) of varying sizes, the appearance of the stone slab will depend on the type of cut applied to the stone. ‘Rasotica’ appears dark due to its organic bituminous component, which loses color and fades in exposed and atmospheric locations.
The renowned Brač white stone is commonly known as ‘Veselje unito’ and ‘Veselje fiorito’, named after the Veselje bay where an ancient quarry operated from 1455 onwards. Over the time three new quarries developed in that area – Sivac, Barbakan, and Punta. Additionally, a gray-white dolomitized limestone (‘Sivac’) is also extracted on the island.
The quality of Brač stone has been recognized since ancient times as an important source of building and sculpting material.
Brač stone has favorable physical-mechanical and technical-technological properties, which is why it was used in the construction of Diocletian’s Palace, the waterfront in Split, the forum in Zadar, the Sea Organ in Zadar, St. James’s Cathedral in Šibenik, the old town of Dubrovnik, the Vatroslav Lisinski Concert Hall in Zagreb, and more. However, it was also used to cover the forecourt of the United Nations building in New York, the White House in Washington, the Parliament building in Budapest, the New Palace in Vienna, and others. The greatest monument to Brač stone is undoubtedly Diocletian’s Palace, which was almost entirely built from Brač stone extracted from quarries between Škrip and the Splitska Bay, from where the stone was transported to Split.
Marija Braut, St. Jacob's Cathedral, Šibenik, 1978, Museum of Arts and Crafts, Zagreb, MUO 52671
Today, stone blocks are extracted using a combination of diamond wire saws and chain saws. After separating the block from the parent rock, it is lowered onto the working platform. Block lowering is done using hydraulic or pneumatic cushions and machine pushing with loaders and excavators. After the primary block is lowered, it needs to be sawn into commercial-size blocks. A gang saw is a machine for sawing commercial stone blocks into a large number of stone slabs of standard thickness and dimensions. Grinding and polishing of marble and limestone are performed after cutting and trimming, once the product has obtained its final shape and dimensions.
Jadrankamen
Dressed stone is stone processed by stone-masonry hand and machine tools. Surface treatment of stone can enhance or diminish certain properties, such as water absorption and resistance to weathering. The final appearance of the surface depends on the tool used and the method of treatment. It can be naturally broken, processed with a hammer, chisel, pick, mallet or ax, etc. Polishing achieves a high gloss, reflective, and smooth surface. Smaller holes or larger pores are filled with epoxy resins. Polishing highlights the decorative properties of stone (structure, texture, and color), protects the stone from weathering (stains, salts, water, aerosols), and thus increases the durability of the stone. The stone surface becomes hydrophobic through polishing.
Stonemasonry School, Pučišća, Brač
Special attention should be paid to the size of pores. Smaller pores lead to greater capillary moisture expansion, while larger pores make the stone more resistant and durable. The durability of the stone also depends on the size of mineral grains. Stone built from finer grains tends to be more durable than that built from coarser grains or stone with large differences in grain size.
When choosing stone, there is an increasing focus on decorative aspects, often neglecting the physical and mechanical properties of the stone.
As a result, damage occurs to the stone due to aggressive urban environmental conditions, poor design, and inappropriate stone selection. Applying architectural stone with a carbonate composition in conditions of acid rain and salt poses a particular challenge, leading to stone exfoliation and intense deterioration.
Brač stone in form of stone slabs is used in construction and architecture as a structural component, such as in arches, vaults, domes, roofs, cornices, stone gutters, staircases, and balustrades. Thin layers of stone (cladding) can be used on interior and exterior walls for decorative and protective purposes, while finely crushed stone is used in construction or as raw material for industry. High decorative quality makes Brač stone preferred material in memorial architecture (gravestones) and sculpture. Contemporary uses of Brač stone include souvenir industry and jewelry.
