Trachyandesite
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Trachyandesite is an extrusive igneous rock with a composition between trachyte and andesite. It has little or no free quartz, but is dominated by sodic plagioclase and alkali feldspar. It is formed from the cooling of lava enriched in alkali metals and with an intermediate content of silica.
A cut block of trachyandesite lava from a volcano in Auvergne, France, used as building stone, forming part of the walls of Clermont-Ferrand Cathedral, France
Mount Tambora
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Mount Tambora, or Tomboro, is an active stratovolcano in West Nusa Tenggara, Indonesia. Located on Sumbawa in the Lesser Sunda Islands, it was formed by the active subduction zones beneath it. Before 1815, its elevation reached more than 4,300 metres high, making it one of the tallest peaks in the Indonesian archipelago.
Caldera of Mount Tambora
Mount Tambora and its surroundings as seen from space
View of Mount Rinjani from Mount Tambora. Viewing distance is 165 kilometres (103 mi).
Size comparison of Mount Tambora ("Pompeii of the East") and Mount Vesuvius ("Pompeii")