Pegmatite

Peggy Pegmatite is 280 million years old. Pegmatites are coarse-grained rocks that often occur as veins in, for example, larvikite. They are formed during the final stage when magma solidifies.

I simply love colors! Just look at me-red, blue, light and dark gray, black and white patches. Or rather, crystals. Not that I look like a polished diamond, but I’m made up of larger and smaller crystals. And if I may say so myself-I’m special, both on the outside and the inside. Geologists are very fond of me, of course because I can have really large crystals, but perhaps most of all because I can contain many different and rare elements. Elements are what everything is made of, both us rocks and you humans, so in a way they’re like tiny building blocks. I also come from molten rock, the same as Lars Larvikite. But I took a very long time to become myself, so my crystals had plenty of time to grow large. After Lars Larvikite and his gang had become the rock larvikite, it was the leftovers of the melt that became me. And when there were many unusual elements left in the melt, I had to become many unusual minerals! You can find me in many different rock types, but right here, on the edge of the Oslo region, you’ll find me together with Lars Larvikite and Synne Syenite!

Facts

Pegmatites are coarse-grained rocks that often occur as veins in, for example, larvikite. They are formed during the final stage when magma solidifies. Such residual melts can contain many different elements, which may be different from those found in more common minerals. The southwestern part of the Oslo region is known for a great diversity of minerals, and it is in the pegmatites that this diversity is found. For example, the element thorium was first identified in a pegmatite vein from here-in the mineral thorite.