Sunday, November 4, 2007

These are few of my favorite stones...

Want to stump a geologist? Ask him to name his favorite stone! Allan gave me a few of his favorites... wow! Pictured at left are garnets, which naturally occur as rhombic dodechedra (* see below). I wouldn't have believed it being handed the small red perfectly formed crystals. They appear to be precisely carved in geometric shapes. He gave me a few pieces of the stones in which they are found, and sure enough, you can see the garnets with their perfect faces embedded in the rock.
The other stone is mazi quartzite, a chromium quartz that shimmers a metallic green. Allan brings back a lot of this rock when he visits Finnmark each year and gives chunks of it to his students. (Finnmark is the name of the county in the extreme northeast of Norway bordering on Finland to the south and Russian to the east. It's the largest county in Norway, larger than the entire country of Denmark, but it only has a population of 73,000.) Here's a link to pictures of the quarry, it's rather amazing:

* About rhombic dodechedra: If you build a pyramid on each face of a cube so that the faces of each pyramid line up in the same plane and the pyramids on the other faces, you'll have this amazing shape. It has 12 identical faces (thus the "dodecahedron" part of the name) and each face is a rhombus, or diamond shape. This solid is space-filling, meaning that if you had a bunch of them, all the same size, they would pack together tightly in 3D space with no gaps between them. Rhombic dodecahedra have many fascinating and beautiful geometric and numeric properties.

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