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Silberquarzit – a fascinating product of nature

Silberquarzit is hard and stable, slip resistant and even resistant to bacteria. Our interest is elemental. Where does the stone get these properties and how can they be measured? How can we reinforce these features with matching materials such as grout? We want to find answers, so we initiate scientific work with partners. We have already found answers to some of these questions:

Straight from the Hohe Tauern window – origin and geology

Silberquarzit comes from a geologically interesting area: The upper schist mantle of the Hohe Tauern window. The Hohe Tauern window is traversed by the Adriatic seam, which marks where the former African and European continent split through tectonic movement of the Earth’s crust. The lowest lying “oceanic lithosphere” was released in the process. These tectonic movements created the “Pennine Sea”; Silberquarzit originates from the resulting sediments. The shifting of the European and African continents over one another extremely compressed the sedimentary rocks deposited at the Adriatic seam under high pressure and temperature conditions. It is believed that the rock transformation took place 250 million years ago at a depth of 10 to 15 kilometers and at temperatures of 600 degrees Celsius. These extreme conditions are what make Silberquarzit one of the world’s hardest natural stones. Rock crystals are commonly found in conjunction with Silberquarzit.

 

 

Silberquarzit is a muscovite quartzite. It is embedded in muscovite schist in vertical parallel lines. These can be several hundred meters long and extend over 20 to 30 kilometers. Silberquarzit has a schistosity in the millimeter to centimeter range. The slabs are split along these lines. Quartzite is quarried in stages and processed at the nearby plant. As a pure quartzite, it has a quartz content of over 90 percent. Another unique characteristic of Silberquarzit is that it can be extracted in relatively large slabs, which is very rare in pure quartzites. Blocks that cannot be split are cut with diamond saws to produce Silberquarzit with a quarry-faced and diamond cut surface. Silberquarzit products range from polygonal slabs in various shapes and sizes, cut format panels and steps to wall stones, block steps, boulders and more. Its extraordinary qualities such as low water absorption, resistance to acids, bases, chlorine and salts, resistance to bacteria, high slip and frost resistance make Silberquarzit ideal for use in wet areas.

 

Extremely dense structure, electron micrographs of Dr. Gerhard Lehrberger, TU Munich
Extremely dense structure, electron micrographs of Dr. Gerhard Lehrberger, TU Munich

High-density quartz structure

Dr. Gerhard Lehrberger and his team at the University of Munich have revealed the composition of Silberquarzit. Their findings: Silberquarzit is over 95 percent quartz – a mineral with the chemical composition of silicon dioxide (SiO2), which forms crystal structures. Each silicon ion is tetrahedrally surrounded by four oxygen ions. Quartz has a hardness of 7 and is considered very stable. Muscovite is one of the most stable micas and contains layers of potassium inside it. These are rarely bioavailable. The high quartz content (with the formation of silica) and potassium prevents the colonization of microbes and has an “antibacterial” effect. Micrographs taken by Dr. Gerhard Lehrberger and his team show the dense structure of Silberquarzit. The muscovite mica flakes are shown in yellow; the quartz grains are visible in black. The flakes come to the surface in quarry-faced products. The unique structure of Silberquarzit gives it various properties.

 

No-slip surface in wet areas

Stepping out of a pool can be slippery. Not with Silberquarzit. Thanks to its quarry-faced surface, Silberquarzit prevents slipping – especially in wet areas. The DIN 51130 standard confirms this and divides materials into five different assessment categories on a scale of R9 to R13. Silberquarzit was grouped in the R12 category and therefore considered “non-slip”. Studies as part of DIN 51097 also demonstrate this. This “ramp test” analyzes slip resistance of barefoot areas under specific angles of inclination. Whereas assessment category A means an inclination angle of 12 degrees, Silberquarzit is still slip resistant in assessment category C with an inclination angle of 24 degrees.

Does not absorb liquids

As revealed through DIN 52102 testing, Silberquarzit has a bulk density of 2.65 t/m³. This high density prevents the absorption of liquids. According to DIN 52103, the water absorption of Silberquarzit is only 0.22 percent by weight. This is by far the lowest of any other natural stone. In addition to water, Silberquarzit also repels oil and other liquids. This makes it ideal for use indoors and even as a kitchen countertop, where red wine and olive oil are easily wiped up. Silberquarzit is “spotless”.

No place for microbes

The stability and density of Silberquarzit combined with the layers of mica give Silberquarzit excellent resistance to bacteria, mold and other germs. A study by the testing service LGA confirmed this: Different rock types were observed for 14 days at 30 degrees Celsius and 97 percent humidity. Only the negative control with glass and Silberquarzit found no bacterial or fungal growth. This natural stone is therefore very appealing for use in spas and wellness facilities.

Weather resistant

The high density and hardness of Silberquarzit make it resistant to frost, acids and salts. It is pressure resistant and can even withstand high-pressure cleaning. The strong molecular structure of Silberquarzit prevents weather-related decay. Silberquarzit is stable. Standard tests confirm:

  • Weathering resistant according to DIN 52104 - B
  • Salt resistant according to DIN 52111 - A
  • Acid resistant according to DIN 52206
  • Pressure resistant according to DIN 52105: 288.7 Mpa
  • Wear test according to DIN 52108: 4.3 cm³/50 cm

Are you interested in our Silberquarzit products?

Find out more about the surface characteristics, colors and application areas of Silberquarzit.