Kuru

Grey Granite

Hard, fine-grained, even-colored, generally grey granite.

For over a hundred years through the grey stone.

The grey granite extracted from near Tampere in the northern end of Lake Näsijärvi, known as Kuru grey granite, is a renowned stone that has been quarried since the mid-1800s. It has been exported worldwide under different trade names, such as Kuru Grey and Royal Grey. Its significance in, for example, the construction of Tampere cannot be overstated. The Tammerkoski rapids, factories, the landscape, and the most recent addition, the Tampere tram, all feature this stone in a central role. Even today, Kuru grey is quarried by several companies in Kurun Ylöjärvi and Teisko district of Tampere. Both areas cover the same rock formation. Kuru grey granite is known for its hardness, even color, fine structure, resistance to weather and wear, making it highly versatile for construction. It is essential to consider the availability of the material in the future when designing projects. Accordingly, there have been numerous sites where the original stones were supplied over a century ago, which have now been extended using the same stone. Check out the geotechnical report on Kuru grey granite.

Polished
Split
Sanded & Polished
Bush-hammered
Flamed

The appearance of the stone is completed with surface treatment.

Desired measurements, shapes, and surface treatments are crafted from granite quarried from the quarry. The surface treatment method heavily impacts the depth of color on the dry stone surface. A glossy surface always exhibits the most potent coloration while a rough surface appears lighter. When the stone is wet, differences in shading caused by the surface treatment level out. Different alternatives for surface treatment include grinding, chiseling, flaming, or splitting. The split surface, also known as rough-hewn, is the closest to the natural rock surface. In ancient times, when stone was crafted by hand through drilling and wedging, the rough-hewn surface was the most prevalent and often the only option for surface treatment. It remains an excellent option in certain building designs such as retaining walls. When producing larger quantities of precisely cut and cost-effective products, such as pavement or building façades, sawed stone products are most commonly used. The sawn surface is mechanically treated, for example, through flaming or bush-hammering. Both methods are cost-effective and allow the natural color and texture of the stone to be beautifully displayed.

Grey granite bush-hammered cap

In a bush-hammering process, the stone surface is mechanically roughened using pneumatic hammers. Larger flat surfaces are processed by an automatic machine, but certain surfaces of finished pieces are processed by hand. Bush-hammering always makes the stone a little bit lighter in color than its natural shade. The surface is evenly rough and straight. Bush-hammered surfaces are commonly used in environmental construction and facades.

Flamed grey granite

When producing flamed stone surface, the surface of the stone is heated with flames and cooled with water spray, which results in surface erosion limited to only the stone surface. The flamed stone surface is rough and straight, reproducing the color and structure of the stone more accurately than a bush-hammered surface. Flamed surfaces are commonly used in environmental construction and facades.

Splitted grey granite

Split stone surface is natural, uneven, and straight-edged. Stone is traditionally split by drilling and wedging and increasingly by hydraulically-powered machines. Advancements in machine technology allow for larger stones to be split mechanically while improving product precision. Split stone is a good option for example in wall stone.

Polished and honed grey granite

Machining and polishing are different degrees of grinding. In machining, the stone surface is gradually treated with a finer grinding stone series until the desired surface fineness is achieved. The color varies depending on the degree of grinding. The darkest and most rich tone is achieved on a polished surface. Polished and matte ground surfaces are used, for example, on facades, environmental furniture, interior stones, and memorial stones.

Grey granite is popular among skaters

The ancient material of stone has found new uses. The properties of Kurun grey granite have been noticed in numerous skateparks, where we have supplied stones. Fine-grained, durable, and even stone provides a good feel for skating. The durability of the stone is of great importance in a location where it is subjected to heavy wear. Modern machinery and the characteristics of machining tools make it possible to create various profiles on the stone.

kuru

Grey Granite

Tampere

Nokia Arena

The main entrance surface areas, planting basins, and main staircases of the arena were made using Kurun grey granite, with guiding attention tiles made from Kivijärvi black granite.

Skate Parks

The properties of Kurun grey granite have been noticed in numerous skateboard parks where we have supplied stones. The fine-grained and even stone provides a good feeling when skateboarding. The durability of the stone is also significant in the location where it is subjected to heavy wear.

Gråbo, Sweden

The state of the tutorial island was implemented with red granite from Taivassalo and grey granite from Kuru.

Saimaa Canal Bridges, Lappeenranta and Joutseno

The block surfaces of the Saimaa canal bridges, as well as the covering and deck stones, were made of Kurun grey granite.

Kviberg park Göteborg, Sweden

Grey solid stairs with a attention stripe were built in the courtyard of the hotel and sports hall.

Mineral composition

Values are in accordance with EN-12407 standard

Mineral %
Plagioclase 32.6 Wt %
Quartz 31 Wt %
Kalimaasälpä 30.8 Wt %
Biotite 3.5 Wt %
Muscovite 1.2 Wt %
Other 0.9 Wt %
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