Sten – Västernorrland

Like several of the other stones in the stone circle, I consist of the rock type granite. However, I am not an ordinary granite by any means. My granite, the beautiful red Nordingrå granite from the High Coast in Ångermanland, is Ångermanland's landscape stone and represents Västernorrland County in the stone circle. I was formed from a magma - a rock melt - that penetrated into the earth's crust and solidified 1580 million years ago, two or three hundred years after most of the bedrock in northern and central Sweden. Along with the red granite, dark gabbro and light anorthosite were also formed. The latter is an unusual rock that consists almost entirely of feldspar. But on the moon it is common, all the bright parts of the moon's surface consist of similar anorthosite.

But I'm red. The red color comes from the fact that I contain so much of the mineral potassium feldspar, which is red. Actually, it's microscopic inclusions of the iron oxide mineral hematite inside the potassium feldspar that give the red color. Anyway, it is beautiful. If you look really closely, you may also see some light translucent quartz and dark biotite or hornblende. But on top of me there is quite a lot of lichens growing, which I think should be washed off so you can see my red color better.

By the way, the fact that you can see me up at the surface of the earth on the High Coast now is because all the overlying bedrock has been eroded away over the course of millions of years, after I was formed. The same applies to all granites and other rocks formed deep in the crust, such as gabbro or different types of gneiss.

A little further inland, at Ragunda, I have a slightly younger brother who also consists of gabbro and granite, and several smaller siblings. There are even more similar granites in Finland and on Åland. If you have been to Åland, you may have noticed that the main island consists almost exclusively of strong red andcoarse granite. It is an older brother of mine. The geologists find it a little strange that these granite magmas penetrated deep into an otherwise stable crust, long after it had formed, and sometimes deep inside a continent. At this time, Sweden and northern Europe were part of a large supercontinent called Columbia (or Nuna), where most of the continents of the time were gathered. Southwest Sweden was close to the edge of this supercontinent, and there was geological activity going on all the time, but central Norrland and Finland were a bit in from the edge. Therefore, the geologists have discussed a lot back and forth how granites like mine actually formed, without being able to agree. I know, but I'm not going to reveal it that easily.

Because such granites are so common in Finland, Finnish geologists have become somewhat of experts on us. In Finnish we are called rapakivi granites, and that name has spread to geologists all over the world. Actually, I'm not too fond of that name, in Finnish it means "rotten stone", but I don't feel rotten at all. But it is true that it is quite easy for us to weather to coarse gravel, that is why we got this name. In Finland, otherwise, rapakivi granite is mined and slabs of it are polished, and used as beautiful and exclusive floor coverings or facade cladding, in houses which have to be extra classy and nice, so in that way it is really not "rotten stone".

Geologist Åke Johansson
Swedish Museum of Natural History