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Andesite (/ ˈ æ n d ə z aɪ t /) [1] is a volcanic rock of intermediate composition.In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite.
The individual crystals in an aphanitic igneous rock are not distinguishable to the naked eye. Examples of aphanitic igneous rock include basalt, andesite, and rhyolite. Glassy or vitreous textures occur during some volcanic eruptions when the lava is quenched so rapidly that crystallization cannot occur. The result is a natural amorphous glass ...
The andesite line is the most significant regional geologic distinction in the Pacific Ocean basin. It separates the mafic basaltic volcanic rocks of the Central Pacific Basin from the partially submerged continental areas of more felsic andesitic volcanic rock on its margins.
The breccias in the Fifes Peak are mostly shades of gray, purple, and red, with angular to subrounded rock fragments cemented by ash. The fragments are a few inches in dimension, rarely a foot long. They are mostly andesite porphyry, pumice, and glass. With fewer rock fragments, the breccias is a buff and tan. Pieces of petrified wood may be ...
The Ica stones are a collection of andesite stones from the Ica Province in Peru, known for their engraved motifs. Largely regarded to be modern hoaxes , [ 1 ] [ 2 ] [ 3 ] the stones in some cases utilize art styles from various pre-Columbian Peruvian civilizations and often depict anachronistic scenes or objects, including dinosaurs and ...
Basaltic andesite is a volcanic rock that is intermediate in composition between basalt and andesite. It is composed predominantly of augite and plagioclase . Basaltic andesite can be found in volcanoes around the world, including in Central America [ 1 ] and the Andes of South America .
Pillow lava at Boatman's Harbour. Oamaru, New Zealand. Pillow lavas are commonly of basaltic composition, although pillows formed of komatiite, picrite, boninite, basaltic andesite, andesite, dacite or even rhyolite are known.
Andesite from St. Saviour's Andesite Formation is in the centre and in the north at Les Rouaux. It is coloured grey and includes some basalt and pyroclastic fallout such as tuff and agglomerate. Porphyritic andesite is dark grey with white crystals of plagioclase feldspar embedded.