Natural stone that is sold under the name of slate is usually a sedimentary rock, but mica shales can also be considered to belong to slates. Mica shales are metamorphic rocks and they have formed through clay shale metamorphism.

Very easy cleaving is natural for slates. Big blocks of slate are not possible to get, so the layers are crammed mechanically free from each other.

Slates are usually dark, which comes from the high carbon content. Slates compose partly of varicoloured clay-minerals, with grain size smaller than 0.002 mm.

Slates are sold either with natural surface or honed surface tiles. Because slates are mechanically relatively soft rocks, then there is no reason to get daunted if the surface of a tile is a little bit grazed. During everyday use, the surface is honed evenly smooth by footwear and the scratches disappear.

When installing slate stone material, always make sure that the back side of the tile is clean. We recommend to wash it over before installation. Also, scratching of the back side and the usage of special products is recommended for better bonding.

Impregnating and imbibition of slates is generally useless, because the water absorbence is close to zero crosswize layers.

Compared to other natural stones, slate has significally greater bending strength, an average of 50 - 80 N/mm2. The volume weight of slates is between 2.7 to 2.8 kg/dm3, water absorbency 0 to 0.5% and they are generally weatherproof. Polishing of slates is not possible.

Mica shales can be recognized by the silky reflection of their natural surface. This comes from the shales (mainly biotites, muscovties and sericites) that have formed during metamorphosis. Mica shales are not always weatherproof. They shouldn't be installed with thin mortar fixing. Similarly to usual slates, mica shales have great bending strength too, an average of 40-80 N/mm2. The volume weight of mica shales is 2.6 - 2.8 kg/dm3, water absorbency 0.2 - 0.4% and wear resistance 15 - 25 cm3/50 cm2. Mica shales are usually sold as tiles with natural surface.