JuraLimestone GmbH, part of the construction holding STO AG, owns 9 quarries of Jurassic limestone. A special quarry of this stone is located in the area of Petersbuch, near the city of Eichstätt in Germany, which was previously developed by the company Neumeyer & Brigl, a family business of Mr. Hans Neumayer and Otto Brigl, now part of JuraLimestone.
The quarry reaches a depth of about 19 m and consists of 25 layers. Here, one can extract the rare Jurassic stone of a special light beige color – JuraLimestone® Jura Cream, which, with appropriate surface treatment, can have an almost white tone with subtle outlines of ancient fossils, giving this stone its world-famous individuality.
Gerhard Ruf - former manager of the company JMS, representing several quarry operators and producers of Jurassic limestone, and now head of the international projects department of JuraLimestone, explains that in the career one can see all 25 layers and the thickness of each of them is determined by nature. "We are working simultaneously at several levels due to differences in color," he explained. "In this quarry, there are 25 layers and very little overburden. You can count all the layers, from the first to the twenty-fifth."
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🔍Jurassic limestone has, as mentioned above, a layered deposition that does not significantly change over many kilometers. This primarily accounts for the relative uniformity of raw material quality for large facade projects and the homogeneity of the color range. The main natural tones of Jurassic limestone vary from beige to dark beige, which are found in the upper layers from levels 20 to 25. Gray tones are also encountered, which are typically used for interior finishing and are located in layers from 1 to 6. Layers 10-11 are usually light shades and serve as the raw material for products with a vein-cut structure, as they have pronounced longitudinal stripes when cut against the natural bedding layer. The Jurassic stone JuraLimestone Jura Cream is found in the "Petersburg" quarry in layers 15 to 17. For comparison, we attach a photo of standard light and dark beige Jurassic stone and Jura Cream.
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🔍Directly at the quarries where raw materials are extracted, teams work that drill the stone to a depth corresponding to the size of the block, then they break out the block with hydraulic machines. After that, the block is lifted up with the help of a tracked front loader. According to Ruf, there is no need to make horizontal cuts – the stone separates from the mass naturally.
One quarry produces from 4000 to 8000 cubic meters of Jurassic marble per year. Moreover, due to weather conditions, it is usually closed during the winter months of December, January, and February.
"It is important to note that this area was very calm," says Ruf. "The movement of rocks here was a rarity. That is why the quality of the stone in this quarry is excellent. A first-class location. We will be able to develop it for another thirty years in a row."