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En skiferhugger med skinnforkle og hammer som står foran en steinblokk av Ottaskifer Pillarguri for å kløve denne i skiferplater.

Shaping 460 million years old Otta slate is a handicraft

Geir got a summer job at the Otta quarry in 1993, and stayed there. With this job, it’s a bit like technology: if it ain’t broke, don’t fix it!

– You have to read the stone in a way that a machine would never be able to do. Each stone is unique, so a stonemason learns to read the stone so as not to damage it.

Possibilities

Outdoors, with the help of Mother Earth, over time, Otta slate, will change colour from muted black/coke grey to a lovely warm golden patina. A unique feature that gives a façade, a roof or outdoor area a completely separate story to tell.

For both indoor and outdoor use, you can choose between different shapes, surfaces and sizes that allow you to create exciting contrasts in, for example, bathrooms, kitchens or other interior areas. You can also let us adapt the slate to exactly what you want. Regardless of the design, Otta slate will remain equally strong, resistant and maintenance-free.

A cabin with reused rust colored Ottas slate on the foundation wall. Wooden barn doors are open to a modern furnished dining room.
Old Otta roofing slate has been reused on the foundation of this beautiful cabin.
A modern bathroom with black Otta slate tiles on the wall and floor in herringbone pattern.
Otta tiles in herringbone pattern create an exciting contrast to the white walls.

Origins

Our traditional slate quarry is situated above Otta at Pillarguritoppen, with a breathtaking view of Gudbrandsdalen and Rondane.

For almost 1000 years, the locals have extracted 460 million-year-old slate from this area and to this day, Otta slate is refined by skilled professionals and craftsmen – right at the foot of the mountain from which it is quarried.

Life cycle

Throughout the area around the slate quarry at Otta, ancient buildings and houses bear a wonderful testimony to why locals have chosen to make use of the slate as a local natural resource.

On roofs and outdoor areas, Otta slate has not only resisted frost, wind, weather and climate change for hundreds of years without maintenance and replacements, it has even become more beautiful. A characteristic created by nature itself, which means that the slate will last for an eternity.

Thin slate slabs of black and brown Otta slate are stacked vertically

Projects

In the quest to build green and achieve environmental certification of new buildings, it’s essential to choose materials with the lowest possible environmental impact. Therefore, not much can compete with a locally sourced, durable natural material with a high degree of manual processing.

Despite its very distinctive appearance, Otta slate is extremely versatile.

Which is why you may well be treading on Otta slate when you enter a Cartier store in New York, or the Hearts on Fire store in Shanghai to buy a diamond ring for your wife.

A diamond shop with black slate tiles from Otta Pillarguri on the floor. In the middle of the room is a table with a stand.
Heart On Fire, Taipei, Taiwan | CAPS Architects
A large room with black slate tiles from Otta Pillarguri on the floor. In the middle of the room is a slate wall that divides the room in Otta drywall.
Scandinavian Golf Club, Copenhagen, Denmark | Henning Larsen Architects
A close-up of a stand clad in black slate slabs of Otta Pillarguri with jewelery from Cartier.
Cartier Paris, France

Visitors can admire both the artworks and the Otta slate in the Van Gogh Museum in Amsterdam, or the Jewish Museum in Berlin. Or perhaps you’re becoming learned and wise at the Boston Public Library or Dartmouth College in the USA – after walking on Otta slate at Oslo Airport.

Take an extra look when you buy the wonderful herbal soaps with essential oils from the nuns at Tautra Monastery or accompany your nephew to his confirmation ceremony in Dombås church!

A modern building with brown facade slate from Otta Pillarguri. The slate slabs have a color of rust which gives a great play of colors.
Boston Public Library, USA | Machado and Silvetti Associates
Tautra Mariakloster with facade slate in brown slate from Otta Pillarguri and glass roof. The slate slabs have the color of golden rust.
Tautra Monastery, Tautra, Norway | Jensen og Skodvin Arkitekter
A modern building with pointed roofs clad with slate from Otta Pillarguri. The building has a slate dry wall of Otta wallbricks.
Scandinavian Golf Club, Copenhagen, Denmark | Henning Larsen Architects

You don’t have to look far to spot Otta slate if you’re on Lidingö outside Stockholm. The “Fyrtornet” (lighthouse) designed by Wingårdh architects, is an apartment building that has become a national landmark, due to its height, unique shape and rust-coloured Otta slate façades.

A modern building with pointed roofs clad with slate from Otta Pillarguri. The building has a slate dry wall of Otta wallbricks.
Scandinavian Golf Club, Copenhagen, Denmark | Henning Larsen Architects
A tall apartment building with round balconies clad with facade slate from Otta Pillarguri in golden colors of rust and black.
Fyrtornet Dalénum, Lidingö, Sweden | Wingårdh arkitektkontor | Photo Nordvästan Tak och Fasad AB
Descent to the subway with Otta facade slate and glass. The black slate slabs in different formats give a pattern on the wall.
Ensjø Metro Station, Oslo, Norway| Flux Arkitekter

What is more natural than choosing stone from the Norwegian mountains when building the world’s first train station inside a mountain? At Holmestrand Mountain Station you’ll be walking on Otta slate both inside the station and on the platforms.

If you drive through Gudbrandsdalen on your Norwegian holiday this summer, look up and enjoy all the beautiful roofs of churches, hotels and farms along the way. They shine like gold, which most of them have done for more than a hundred years.

Frequently asked questions about slate

It has an unlimited lifespan. For a natural stone to have a long lifespan, it must have a mineral composition that makes it weather-resistant. Our slate consists of highly durable minerals. In addition, they have a mineral structure that is dense and thus strengthens its technical properties. Our three types of slate are positioned within the top 10 in the world in terms of durability.

Our slate is from Norway and Sweden, and all production is done locally by our stonemasons. Slate is split by hand into its natural layers, unlike marble and granite, which are cut mechanically into sheets using a multi-blade saw. However, with a lifespan of > 100 years, slate is often a cheaper alternative in terms of lifespan. The installation cost is largely the same, whether you choose slate or an affordable material.

Slate is a 100% natural material. Our slate from Otta, Oppdal and Offerdal consists of highly durable minerals such as quartz, felt spat and mica. The minerals have a favourable structure that is dense and further strengthens its qualities. Through pressure and temperature, the deposition of sand and clay in rivers and on the seabed has been transformed into rock slate for hundreds of millions of years.

You save the environment from a more than 700% increase in CO2 emissions compared to a ceramic copy. Genuine slate tiles can be supplied with falling lengths that create a beautiful floating look. This format cannot be achieved by using ceramic copies. Choosing local genuine slate also supports sustainable production and local value creation.

The quality of Scandinavian slate is unrivalled. There are old types of rocks where time, pressure, temperature and transformations have developed the slate types into solid materials. The ice ages also contributed to removing much of the younger and weaker rocks that were originally above the slate sites we have today. Most types of slate from other parts of the world are younger, they have not been exposed to temperature, pressure and transformation in the same way as the Scandinavian slate types. Norwegian slate is also local and has a high degree of handicraft – which combined give it a record low environmental footprint.

Minera Skifer has three slate quarries, two in Norway and one in Sweden. Oppdal slate is light grey, the slate from Otta in Gudbrandsdalen is black or rust-coloured, and the slate from Offerdal in Jämtland is deep grey.

Yes, slate is a 100% natural material. Hundreds of millions of years ago, sediments of sand, clay and gravel sank to the bottom of the sea. There it was pressed together into layers, before it became slate under high pressure. Our slate is extracted from Norwegian and Swedish mountains and refined by local stonemasons right at the foot of our three slate quarries.

Yes, local slate from the Scandinavian region has an extremely low climate footprint. It is a 100% natural material that is largely processed by hand, requires minimal maintenance, is everlasting, and can be recycled and reused.

Light Oppdal slate is a medium-grain, rock-speckled gneis mica quartzite slate. Otta slate is a dark slate from the type of rock called Phyllite slate. Offerdal slate is a quartzite from the rock type felt spat metasandstone.

For a slate to have a rust colour, a slate type that can develop a rust patina must be used. In Scandinavia, only Otta slate from Gudbrandsdalen in Norway has a mineral composition that provides this property. Rust develops naturally over time due to weather and wind, and becomes increasingly beautiful over years.

Read about Otta slate’s development of a beautiful rust patina here.

No, our slate must not be impregnated. However, for some applications, it would be advisable to recommend impregnation, as it provides protection against stains and dirt while also facilitating cleaning. For example, it is a good idea to impregnate worktops that are exposed to grease spills, etc.

Yes, slate has very good breaking strength and flexibility. For driving on slate laid in cement mortar or on concrete slabs, the slabs should be at least 2 cm thick. If the slate is laid in gravel, the surface should be stable, well compressed and frost-free, and the slate should have a minimum thickness of 4 cm.

No. Our three slate types in natural surfaces are 100% non-slip (with the highest classification) and are therefore very suitable for external areas such as terraces, staircases and the like. We also supply slate in finished surfaces that are non-slip. All our slate surfaces have been tested and the slip resistance has been documented with an R number, which is a standard for testing slip resistance and is used for ceramic tiles, among other things. See our product datasheets for test results.

Yes. Our slate from Oppdal, Otta and Offerdal is all 100% frost-proof and therefore very suitable for use in a tough Nordic climate.  The porosity of a material is calculated by measuring the maximum amount of water that it attracts. In general, porous materials with high water uptake are the least strong and durable. All of our slates have water uptake far below what the European standard states as a limit for frost protection (NS-EN 12326-1: water absorption ≤ 0.6). See more in our product datasheets here

Yes. Our slates are water-resistant and can be installed in pools, fountains and the like. With a very low level of water absorption, they are therefore also 100% frost-proof.

Yes, Minera Skifer’s three types of slate can withstand salt. However, over time, large quantities in humid climates can affect the minerals and cause a colour change in the surface– a patina. This has no impact on the technical quality of the slate, i.e. the function, durability and lifetime remain unaffected.

Yes. Our slate is non-slip and can withstand moisture and chlorine from a pool. Offerdal slate is particularly suitable for this (test-documented), and has been widely used for this purpose in Europe for decades. Our three types of slate can all be used both in the pool itself or around the pool. Otta slate and Lys Oppdal slate should be avoided in the actual zone transition between water and air.

Yes. It is a good idea to lay outdoor heating cables under slate that is glued on concrete or laid in gravel.

This is contingent on insulation under the heating cables. There are, among other things, heating cables mounted on insulating mats intended for this purpose.

 

 

No. Slate in its natural surface can withstand studs and have no unfortunate consequences. On floors where the surface of the slate is either brushed or sanded, we do not recommend the use of studs.

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