Aracar
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Aracar is a large conical stratovolcano in northwestern Argentina, just east of the Chilean border. It has a main summit crater about 1–1.5 kilometres in diameter and sometimes contains crater lakes a
Aracar from the Space Shuttle, January 2003
Andesite
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Andesite is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained to porphyritic in textu
Aracar
…1.5 km (0.93 mi). They have cancelled out the prior landscape. These lower lava flows reach the Salar de Taca Taca and extend south-southeast. The main andesitic cone is 900 m (3,000 ft) high and 5 km (3.1 mi) wide, forming on top of older dacitic lava flows. The dacite flows which form the edifice's bulk are…
A sample of andesite (dark groundmass) with amygdaloidal vesicles filled with zeolite. Diameter of view is 8 cm.
QAPF diagram with basalt/andesite field highlighted in yellow. Andesite is distinguished from basalt by SiO2 > 52%.
Block lava at Fantastic Lava Beds near Cinder Cone in Lassen Volcanic National Park
Photomicrograph of andesite in thin section (between crossed polarizers)