Minerals under the microscope

I did some microphotographs of thin sections this week. Fort hose unfamiliar with geology: thin section is a very thin and polished slice of rock prepared to study with polarising microscope. My thin sections are a bit more thick then usual (about 200 micrometers) – which results in pretty strange colors in the microscope. All of the thin sections are from various lithium rich pegmatites – these are special vein type rocks extremely enriched in rare elements like lithium, beryllium, cesium, niobium or tantalum.

Photos were made with the Olympus microscope and attached DSLR camera. Real width of the photos is about 2-3 mm.

thin section of mica in polarising microscope

Big flake of mica with green tourmaline needle on the left side. The other grains are quartz.

thin section of lepidolite mica and tourmalines

The banded flakes are the Li-rich mica (lepidolite). The big pink and blue grains in the middle are Li-rich tourmalines (elbaite). the other grains are again quartz.

thin section of quartz and k-feldspar

The purple and blue-yellow parts are various types of intergrown feldspars, the left rim is made of the quartz.

thin section with lepidolite, elbaite and quartz

The big blue-purple grain in the left part is quartz and right to it is banded flake of Li-mica (lepidolite). The colorful grains above the mica are all Li-tourmaline (elbaite).

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