Marbles and how they are created
Categories, basic quality characteristics and uses of marble
What would happen to all cultures if there were no buildings, structures and objects to tell their story? How would we know what happened? If we think about it through a historical and at the same time technocratic perspective, matter around us takes on dual significance for humankind. On the one hand, it serves a practical purpose, for example, a house which is created for the habitation of a family, and on the other hand, it can mark a historical landmark, of a period, that stands upright through the years, such as the Parthenon in Athens.
We could define matter as a component of all natural objects that have mass, whether those objects are natural or artificial. As for its characteristics, we can consider the texture, appearance, durability, and the ease of discovery or construction of the material. Human beings are surrounded by matter, exploit it and use it to their benefit.
The main factor determining the value of the material is its durability over time. Quarry minerals and ores are among those with a long life span and are divided into three (3) categories:
- Marbles, slates and other decorative stones, (see below);
- Aggregates, which come from the extraction of natural deposits of fragments, extraction of suitable rocks and which are used for the preparation of concrete or mortar (marble dust and limestone rocks);
- Industrial minerals, clay and marble rocks used in the cement industry but not marbles or aggregates (e.g. bentonite, chalk, gypsum, etc.).
What is marble and how is it created?
Marble is a rock that is characterized by an intense glow and etymologically comes from the ancient word “marmaros”, which means “bright stone”. Marble is the result of the metamorphosis of limestone (sedimentary carbonate rocks) by heat and pressure in the earth’s crust. It consists mainly of the mineral calcite with other minerals from clay, quartz, muscovite, pyrite, iron oxides, chlorite, graphite, etc. usually found in its mineralogical composition (impurities).
Commercially, the term marble refers to many structural and decorative carbonate stones mainly of a composition such as limestone, etc.
Marble is a prime example of how natural processes can change the structure and appearance of a material. Of course, the commonly accepted image of marbles shows them as white and imposing, which is partly true. Marbles are not only white but are characterized by a variety of colors and natural patterns (veins). The variations are a consequence of small amounts of impurities of other minerals, such as those mentioned above, as well as grain size.
What is the marble area?
The exploitation of marble has geographical and topological characteristics and is predominantly mined mainly with surface exploitations. The marble is extracted using wire cutting or other special equipment. In addition to the surface exploitation, there is also the possibility of underground exploitation.
Marble areas are characterized as geographical units with extensive marble deposits which are located in specific geotectonic zones.
Greece is one of the countries that supply the global community with marbles and their derivatives. This sector is export-oriented and is one of the sectors in the country’s economy that can compete with international markets.
The modern quarry centers of the Greek territory are located in the region of Eastern Macedonia and Thrace, in the areas of Kavala, Drama and Thassos. More than 80% of the total exports of Greek marble come from this region, with the following as the main quarrying sites:
- Thassos (Thassos Snow White, Krystallina Thassos, Prinos)
- Towers (Pirgon)
- Volakas (Volakas Haemus, Volakas Electron, Elba Blue, Venus Vox)
- Granite-Fortress (Mistral, Ariston, Fortress, Delos)
- Nestos (Hemarus Gray)
- Paggaio, Stenopos, Makrychori, Limnia, Elafochori, Piges, Dysvato, Vathilakkos, Palea Kavala, Nikisiani.
Elba Blue marble quarry | Volakas, Drama, Greece
Categories & basic marble characteristics
In terms of commercial exploitation, marble is considered to be any crystalline sedimentary or metamorphic rock with a predominately carbonate composition which can be processed. It is a rock composed primarily of calcite or dolomite, as well as their combination.
Calcite (the main component of limestone) offers the characteristic white and grayish-white shades while, at the same time, giving the crystalline character of the rock. In contrast, dolomite is a carbonate mineral of calcium and magnesium. It is particularly similar to calcite and the only way to distinguish their differences is when the powdered mass is diluted and cold hydrochloric acid (HCl) occurs in the powdered mass. Then the calcite shows a strong effervescence, while the dolomite is weak or not at all.
Other impurities that cause structural changes in the mineralogical material are: a) iron oxides, which, depending on the content of the marble, give them a color from light yellow to dark red, b) olivine, which gives the marbles a greenish hue and c) carbonaceous impurities, which give the marbles gray to black shades.
What does the quality of the marble depend on?
The quality of marble is determined both by structural factors of the methods that created the material and by external factors, such as its processing. As already mentioned, the mineralogical composition of the material is what determines the color of the marble.
In addition, impurities of foreign materials are factors regarding the durability of the marble. In the figure “6 Myths regarding the durability of marble”, you can see how the impurities of foreign materials contribute to the durability of the marbles and their basic technical specifications.
At the same time, the existence of veins, the color of the background, the patterns created, which define the visual aesthetic effect that will always be visible, but also the availability of stock of the material, determine, to a large extent, the commercial value that a marble slab can acquire.
Uses of marble
It would not be an exaggeration to say that marble has been used for centuries in architecture and construction as a building and aesthetic material. For several decades, marble was considered accessible only to luxury and imposing constructions, something that has been overturned in recent years. Marble is now widely used in any type of construction or decorative work, whether small or large in scale. In addition, it has “proved” that it can meet the strict requirements of designers, decorators, project builders and sculpture artists.
Modern marble applications are almost limitless. Technology, but also technical solutions, now exist to enable this material to dominate the market of building materials with exterior applications (homes, commercial buildings, churches, etc.) but also interior ones such as (a) kitchens, kitchen counters, (b) flooring, (c) wall cladding, (d) baths and hygienic areas (e) furniture (f) stairs etc. Thus, the limits of the utilization of the material are limited to the type but also to the creative characteristics of the project itself.
The Greek marbles
Greek marbles are known in the global community because of the masterpieces of architecture and sculpture of ancient Greece. This is one of the main reasons for their high demand and export character. Examples of well-known marbles that rank the country as one of the most important exporters are the white and semi-white marbles of Drama, Kavala and Thassos and Penteli and Dionysos.
Moreover, Greece is considered the country with the largest variety of light and light-colored marbles. In addition to white and off-white, there are many types of colored marble, such as gray, green, black, red, etc. Laboratory tests have shown that Greek marbles are characterized by excellent technical specifiacations and can meet high quality constructions.
Some of the white Greek marbles are considered to be among the best in the world. However, there is one more element that reinforces their importance: the reserves of quarry deposits in Greece are considered huge. In fact, many even consider them practically inexhaustible.
The Stone Group International marbles
Stone Group International currently has nine (9) quarries, five (5) production units and more than four (4) decades of know-how. Many white, semi-white and colored marbles are mined daily from these quarries, while the decades of know-how and use of high technology in mining, processing, but also in our production processes, guarantee the response to the requirements of each project.