Magazine

This collection of articles is a knowledge base for those professionally involved with the international natural stone industry and adyacent fields. All articles are copyrighted by Graniteland, unless otherwise noted.

Which criteria should I use to choose my supplier?

The process of natural stone and the “make or buy” in the large production areas of Massa Carrara and Verona (Italy). Visiting one of the thousand companies working in natural stone field to check material during his working process, we may be accompanied in several small workshops where we can see our material being finished. It might even happen that two different natural stone suppliers introduce us in the same workshop — and then we are completely mixed up.

First orbicular granite quarry opened

The worldwide first quarry of an orbicular granite with spheres diametres ranging from 15 to 18 cm was recently opened in Savitaipale, in eastern Finland. Due to the limited quarry size, the production company does not offer blocks but processes the material directly at the well equiped factory near by the quarry.

What is sedimentary rock?

Sedimentary rock is one of the three main rock groups (along with igneous and metamorphic rocks) and is formed in three main ways—by the deposition of the weathered remains of other rocks (known as clastic sedimentary rocks); by the deposition of the results of biogenic activity; and by precipitation from solution. Sedimentary rocks include common types such as chalk, limestone, sandstone, and shale.

What is Feldspar?

Feldspar (from the German Feld, field, and Spat, a rock that does not contain ore) is the name of an important group of rock-forming minerals which make up perhaps as much as 60% of the Earth's crust. They crystallize from magma in both intrusive and extrusive rocks; they occur as compact minerals, as veins, and are developed in many types of metamorphic rock. They may also be found in many types of sedimentary rock.

What is Travertine?

Travertine is a white concretionary form of calcium carbonate that is usually hard and semicrystalline. It is deposited from the water of mineral springs (especially hot springs) or streams holding lime in solution. Extensive deposits exist at Tivoli, Italy, near Rome.

What is Quartzite?

Quartzite is a hard, metamorphic rock which was originally sandstone. Through heating and pressure usually related to tectonic compression within orogenic belts, the original quartz sand grains and quartz silica cement were fused into one. Pure quartzite is usually white to grey. Quartzites often occur in various shades of pink and red due to varying amounts of iron oxide. Other colors are due to impurities of minor amounts of other minerals.

What is Slate?

Slate is a fine-grained homogeneous sedimentary rock composed of clay or volcanic ash which has been metamorphosed (foliated) in layers (bedded deposits). Slate can be made into roofing shingles ('roofing slates' in the UK) because it has two lines of breakability: cleavage and grain. This makes it possible to split slate into thin sheets.

What is Tuff?

Tuff (from the Italian "tufo" and pronounced "toof") is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption. The products of a volcanic eruption are (a) volcanic gases, (b) magmas, and (c) steam from water heated by the magma. Where all three interact violently, especially where there is an abundance of water, the magma is blown apart. If the resulting pieces of ejecta are small enough, the material is called volcanic ash, consisting of sand-sized or smaller particules. These particles are small, slaggy piece of lava that have been tossed into the air by outbursts of steam and other gases and have become vesicular by the expansion of the gases within them while they were still plastic.

What is Basalt?

Basalt is an extrusive igneous rock, sometimes porphyritic, and is often both fine-grained and dense. Basalt in the tops of subaerial lava flows and cinders will often be highly vesiculated, imparting a lightweight "frothy" texture to the rock. The term basalt is often casually applied to shallow intrusive rocks with a composition typical of basalt, but rocks of this composition with a phaneritic groundmass should generally be referred to as gabbro. The crustal portions of oceanic tectonic plates are predominantly made of basalt.

What is Gneiss?

Gneiss is a common and widely distributed type of rock formed by high grade regional metamorphic processes from preexisting formations that were originally either igneous or sedimentary rocks. Gneissic rocks are coarsely laminated and largely recrystallized but do not carry large quantities of micas, chlorite or other platy minerals.

What is Sandstone?

Sandstone is an arenaceous sedimentary rock composed mainly of feldspar and quartz and varies in colour (in a similar way to sand), through grey, yellow, red, and white. Since sandstones often form highly visible cliffs and other rock formations, certain colors of sandstone may be strongly identified with certain regions. For instance, much of the American West is well-known for its red sandstones.

What is Limestone?

Limestone is a sedimentary rock composed of the mineral calcite (calcium carbonate). The primary source of this calcite is usually marine organisms. These organisms secrete shells that settle out of the water column and are deposited on ocean floors as pelagic ooze (see lysocline for information on calcite dissolution). Secondary calcite may also be deposited by supersaturated meteoric waters (groundwater that precipitates the material in caves). This produces speleothems such as stalagmites and stalactites. Limestone makes up approximately 10 percent of the total volume of all sedimentary rocks.

What is Marble?

Marble is metamorphosed limestone, composed of fairly pure calcite (a crystalline form of calcium carbonate, CaCO3). It is extensively used for sculpture, as an building material, and in many other applications.

What is Granite?

Granite is a common and widely-occurring group of intrusive felsic igneous rocks that form at great depths and pressures under continents. Granite consists of orthoclase and plagioclase feldspars, quartz, hornblende, biotite, muscovite and minor accessory minerals such as magnetite, garnet, zircon and apatite. Rarely, a pyroxene is present. Ordinary granite always carries a small amount of plagioclase, but when this is absent the rock is referred to as alkali granite. An increasing proportion of plagioclase feldspar causes granite to pass into granodiorite. A rock consisting of equal proportions of orthoclase and plagioclase plus quartz may be considered a quartz monzonite. A granite containing both muscovite and biotite micas is called a binary granite. The average density is 2.75 g/cm3 with a range of 1.74 to 2.80.

What is Igneous Rock?

Igneous rocks are formed when molten rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. This magma can be derived from either the Earth's mantle or pre-existing rocks made molten by extreme temperature and pressure changes. Over 700 types of igneous rocks have been described, most of them formed beneath the surface of the Earth's crust. The word "igneous" is derived from the Latin ignis, meaning "fire".

Is there only granite and marble?

When looking at natural stone shops, they often seem to sell only two kinds of natural stone – granite and marble. However, the marble tiles for your living room, or the granite countertop for your kitchen may well be some other type of natural stone.

Why is granite and marble so expensive?

"Granite and marble is expensive" is an often heard assumption. While many years ago this statement was – for most of the materials – true, today it is far less the case.

Is Granite radioactive?

A popular myth about granite is its (possible) radioactivity. Let's take a closer look at this matter and find out about the radioactivity of granite and other natural stones.

Definitions of Thermal Properties of Natural Stone

This is a growing list of thermal properties of natural stones and related materials.

Definitions of Mechanical Properties of Natural Stone

This is a growing list of mechanical properties of natural stones and related materials.

Definitions of Chemical Properties of Natural Stone

This is a growing list of chemical properties of natural stones and related materials.

Quarry Equipment — General considerations

The main quarrying methods are drilling and diamond wire cutting. In many cases also chain cutting is used but only for marble or travertine. As for tool costs, drilling on marble is about 0,25 USD, on granite about 1 USD per drilled linear meter. Consumption of diesel fuel by the compressor is about 7 l of diesel per hour, for each hammer. That means about 0,15 l of diesel for each hp per working hour of the compressor. The drilling speed depends on the type of rock. In principle it ranges form 50 to 80 cm/min with the new generation of pneumatic hammers.

Natural Stone and Adhesives

Natural stone and adhesive? Yes, but which adhesive? What kind of adhesive has which characteristics? Which characteristics of the adhesive are relevant for my gluing? These questions and many other different questions are often asked, which have to do with natural stone. Unfortunately it is not possible to supply a simple answer, due to the many varied natural stones and fixing methods.

Gang Saw versus Diamond Wire Saw

The big costs of a granite gang-saw are for the machine itself (about 200.000$) and for the foundations (about 25.000$). Anyway, both machines have their own specific field of application. The gang-saw is more suitable for mass production of thin slabs. In fact, normally there have to be used two (or four, or eight) machines in order to guarantee a continuous material output to the polishing line. As the machine needs about 2 1/2 days for cutting one loading, it is necessary that while one machine is working, the other machine can be unloaded.

The Stoertebeker House in Hamburg

Natural stone works in a high-class office and commercial building in Hamburg, realised masterly carried out with Mapei-products

Price increase for Chinese Marble and Granite

On Friday, September 15th, we received the following statement from the Chinese Government: China will abolish export tax rebates on coal, natural gas, minerals and some primary wood products from 15th, Sep.2006 and in...

A NEW STONEHENGE FOR THE NEW MILLENNIUM

Whilst civilisations have come and gone over the last 5,000 years, Stonehenge remains as a sentinel standing on England’s green and pleasant land. A formidable architectural feat, the geometry, craftsmanship and grandeur of the site was unprecedented for its time.

SECRETS OF THE PRESELI BLUESTONES

I first visited Stonehenge as a small child and became fascinated by what to me seemed a place of magic and fairytales. During the 1980s I lived in the Preseli Hills in West Wales, near to the actual source of the inner Bluestone circle and began to realise that there was much more to Stonehenge than I had ever imagined.

Growing Importance of BeijingStoneTech

Since its inaugural event in 1994, STONETECH boasts a history of 13 years. Rotating every year in Beijing and shanghai, this is the original and best supported event in China stone industry. Also it enjoys the support of the key industry organizations including CCPIT Building Materials Sub-council and China Stone Material Industry Association.

Excellency from the Netherlands

To survive in a world of extreme competition, it's essential to find your own way. This company shows, that with exlusive material, excellent workmanship and dedication to the job you're doing it is not only possible to survive, but grow instead and make your business profitable.

Spaceship Earth

Spaceship Eart is a monument for late David Brower, the American environmentalist. It was conceptualised by the well-known Finnish-American artist Eino, the stone work was done by GRAMIL in Cachoeiro, who are also the quarry owners of this unique material (Azul do Mar). The bronze applications symbolizing the continents were applied by the artist himself. The sphere has a diametre of 15 ft (4,57 m), the base (Preto Aracruz) has the size 240 x 240 x 100 cm

FVHF develops new construction quality assurance protocol for natural stone cladding

A new construction quality control checklist, compliant with standards issued by FVHF and GTÜ (the German Association for Technical Quality Monitoring), has been produced for natural stone ventilated rainscreen cladding systems.

System-built: natural stone ventilated rainscreen cladding

At this year’s Stone+tec exhibition in Nuremberg, FVHF-member KEIL-Befestigungstechnik, presented their new system technology for large-size natural stone cladding panels.