HVAÐIR ERU MÝKRI NÁTTÚRUSTEINAR OG HVAR HÆGT AÐ NOTA ÞA? landslagssteinn

Af hverju eru sumir náttúrusteinar considered to be soft when they all appear to be hard? The answer lies within ‘relative’ hardness. Mohs scale of hardness was invented in 1812 and compares the relative hardness of ten minerals. Diamond is the hardest and rates a 10, while granite is the toughest natural stone at 6. Limestone comes in at 3 as does its metamorphic counterpart, marble. Softer stone is easier to dress or carve but does not wear or weather quite as well as harder stone. Here we discuss some of the more popular soft stones along with suitable applications.

Óreglulegir steinar

Setberg

Kalksteinn, sandsteinn og leirsteinn eru algengustu gerðir af setbergi. Þau mynduðust við gífurlegan þrýsting, yfir milljónir ára, sem barst niður á set sem hafði fallið á hafsbotninn.

Slate

The layers in slate are described as being “foliated” and they are easily split apart to create whatever thickness is required. UK slate is considered to be hard and was traditionally used as roofing, while soft slate is found in China, Spain, Italy and the USA. With a broad range of natural slate colours, a multiple array of designs can be achieved, from contemporary to classic, rustic to refined. Slate is often recommended for high traffic areas, thanks to its remarkably durable composition. It is also non-porous and does not easily react with acid liquids. It is fire proof, weather resistant and achieves good slip resistance dues to its riven finish.

kalksteinn

Limestone is a very common building material and is formed mainly from the mineral calcite, derived from the calcium in bones and seashells deposited over the millennia and forced together through pressure. While it also contains magnesium, it is harder and more weather resistant, and can also be polished. Portland stone from the eponymous island in Dorset is probably the single most famous type of limestone and was used to build many of London’s great buildings. It is used for external cladding as well as paving, fireplaces and other internal and external decorative features. Its soft colours are its trademark visual attributes.

Sandsteinn

Sandsteinn var líklega mest notaði byggingarsteinninn fyrir 1800, fyrir allt frá brýr til virðulegra bygginga. Eins og ráða má af nafni þess myndast það þegar sandur, lífræn efni, kalsít og ýmis önnur steinefni voru runnin saman undir ótrúlegum þrýstingi í gegnum árþúsundir. Fáanlegt annað hvort með grófri eða fínni áferð og hefðbundið í mattri áferð. Aðallega krem, rautt eða grátt í Bretlandi, litur þess fer eftir viðbótarsteinefnum sem eru í því. Kísil gefur hvíta, á meðan járn gefur rauðbrúnan blæ. Helstu notkunarsvið þess eru veggir og gólfefni eða slitlag að utan.

Marmari

Marmari er kalksteinsafleiða sem myndast við myndbreytingu risastórs hita og þrýstings yfir milljónir ára. Þó að það sé tiltölulega mjúkt miðað við aðra steina, hefur marmari tilhneigingu til að fægja ótrúlega vel. Hefðbundið er marmari notaður í hurðir og hjálpar til við að skapa hágæða áferð.