Diorite
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Diorite is an intrusive igneous rock formed by the slow cooling underground of magma that has a moderate content of silica and a relatively low content of alkali metals. It is intermediate in composit
Orbicular diorite from Corsica (corsite)
Hornblende diorite from the Henry Mountains, Utah, US
Naqada II jar with lug handles; c. 3500–3050 BC; height: 13 cm (5 in); Los Angeles County Museum of Art (US)
Statue of Gudea I, dedicated to the god Ningishzida; 2120 BC (the Neo-Sumerian period); height: 46 cm (20 in), width: 33 cm (10 in), depth: 22.5 cm (8.9 in); Louvre
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
Diorite
…Diorite is found in mountain-building belts (orogens) on the margins of continents. It has the same composition as the fine-grained volcanic rock, andesite, which is also common in orogens. Diorite has been used since prehistoric times as decorative stone. It was used by the Akkadian Empire of Sargon of…
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)