Kuru

Black Diorite

Fine-grained, dark-black diorite that is adorned with white veins and spots.

Black on White

Kuru Black diorite is quarried from the north of Tampere, near Murole Canal. The stone has established its position as a special building and environmental stone in Finland. It has been quarry since the 1970s. Kuru Black is suitable for use in all outdoor and indoor locations.

Polished
Splitted
Sanded and polished
Bush-hammered
Flamed

The appearance of the stone is finished with surface treatment.

Granite quarried from Kalliope is crafted into desired dimensions, shapes and surface finishes. The finish greatly affects the depth of color in the dry stone surface. A polished stone surface is always the most vibrant in color, while a rough surface is the lightest. When the stone is wet, the differences in color resulting from the finish are evened out. Different surface finish options include grinding, chipping, falming or splitting. The split-finish, or so-called split surface, is the closest to a natural rock surface. In the past, when the processing of stone was done manually by drilling and chiseling, the split finish was the most common and often the only option for surface finishing. It is still a good choice today in certain structures, such as stone walls. When larger units are desired to be manufactured precisely and cost-effectively, such as street pavements or facades, products sawn from the stone are most often used. The sawn surface is mechanically treated, for example by burning or cross-hatching. Both methods are cost-effective, and the natural color and texture of the stone are beautifully visible as a result.

Black 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 black 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 black granite

Split stone surface is natural, uneven and straight. Stone is traditionally split by drilling and wedging, and increasingly with hydraulic presses. Advancements in machine technology allow for larger stones to be split while improving accuracy. Split stone is a great option for wall stones.

Polished and honed black granite

Matta honing and polishing are different levels of abrasion. In honing, the stone surface is gradually processed with a finer grinding stone series until the desired surface fineness is achieved. The color varies depending on the degree of honing. The darkest and fullest shade is achieved on a polished surface. Polished and matt honed surfaces are used, for example, in façade surfaces, environmental furniture, interior stones and memorial stones.

Kuru

Black Diorite

Tampere

Tampere Tramway Project

We have supplied the project with curbstones, paving stones, and street pavement stones for Hämeenkatu, Niemenranta, and Hervanta. The materials used are Kurun grey, Kurun red-brown, and Kurun black granite.

Mineral Composition

Values are compliant with EN-12407 standard.

Plagioclase 57 Wt %
Amphiboles 10 Wt %
Bio-titane 21 Wt %
Ilmenite 6.4 Wt %
Magnetite 4.9 Wt %
Clinopyroxene 6 Wt %
Apatite 1 Wt %
Quartz 2 Wt %
Other 1 Wt %
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