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GeoPicture of the week: The Mexican hat

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When you look at these rocks – it’s quite easy to understand why they’re usually called ‘The Mexican hat’: The Mexican hat is a rock formation in south-central San Juan County, Utah, United States. Interestingly, it’s the name of a mini-village (named after the formation), with 31 people inhabiting it. The formation is a 60-foot (18 m) wide by 12-foot (3.7 m) thick, rock outcropping on the northeast edge of town which can be climbed to via two different routes. ……

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GeoPicture of the Week: What Causes the Colour of Gemstones

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You may have wondered exactly what is it that makes gemstones so brightly colored, and if you were curious enough to actually pursue that question, you found out that it’s all chemistry. This picture explains it: Most minerals are actually colorless in their pure form, and they are colored by impurities. The color itself is caused by the different absorption of different wavelengths. Minerals absorb some wavelengths and reject others – the ones which are rejected are the color we see. For example, an object that absorbs all wavelengths of visible light that pass through it, but does not absorb red light, will appear red. For a more thorough explanation…

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GeoPicture of the Week: The Lion Rock in Sri Lanka

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The Sri Lankan lion rock (Sigiriya) is an ancient palace of archaeological and geological importance. The site is dominated by a massive column of rock nearly 200 metres (660 ft) high. According to the ancient Sri Lankan chronicle the Culavangsha, this site was selected by King Kasyapa (477 – 495 CE) for his new capital. He built his palace on the top of this rock and decorated its sides with colourful frescoes. Sigiriya today is a UNESCO listed World Heritage Site. It is one of the best preserved examples of ancient urban planning, and it looks simply amazing…….

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GeoPicture of the Week: Geologic Faults

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This picture from Cornell University really encapsulates the beauty of a geologic fault – it’s like someone took it from a text book and slammed into real life. In geology, a fault is a planar fracture or discontinuity in a volume of rock, across which there has been significant displacement along the fractures. You can see how the different layers (strata) of rock moved relative to each other…….

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GeoPicture of the Week: Perfect Pyrite cube

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  Quite an awesome picture of a single pyrite crystal, isn’t it? I always find it fun that when they see something like this, most people don’t think it’s natural, that it’s somehow man made or at the very least cut by man – but that’s not really how it works. Pyrite usually forms cuboid crystals, and sometimes they are purely cubical, with some small imperfections – like here on the corner, for example. That’s just the geometry of the molecules – they arrange themselves in a cubic frame. Pyrite is the most common sulfide minerals. It’s metallic appearance and luster make it look somewhat like gold, which is why it’s…

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GeoPicture of the week: Uvarovite, an uncommon type of garnet.

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Garnets are a diverse group of minerals, most of which vary in color from brown to black-ish. Uvarovite however is a deep green, really lovely to look at. The different species are pyrope, almandine, spessartine, grossular (varieties of which are hessonite or cinnamon-stone and tsavorite), uvarovite and andradite. Here are some remarkable pictures of other garnets:        ……

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GeoPicture of the week: Mind blowing Bismuth

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This is Bismuth – it is a natural chemical element which chemically resembles arsenic and antimony. Elemental bismuth may occur naturally, but this form does not occur naturally – it was developed in a lab. Still, it’s just mind boggling how beautiful it is!……

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GeoPicture of the Week (2): Volcanic eruption seen from the space shuttle

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In this incredible capture taken on 30 September 1994, we see a major eruption of Klyuchevskaya Sopka as seen by the astronauts aboard the Space Shuttle Endeavour. It is yet another testament of the immense power that volcanoes have, as the ash rose 60.000 feet into the air (almost 19.000 meters) and spread as far as 640 miles (1,030 km) southeast from the volcano. Klyuchevskaya is a stratovolcano built up by many layers (strata) of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic explosive eruptions and quiet eruptions, although there are some with collapsed craters called calderas. Its first documented eruption was in 1697…