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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 . It is fine-grained ( aphanitic ) to porphyritic in texture, and is composed predominantly of sodium-rich plagioclase plus pyroxene or hornblende .
Andesine occurs in intermediate igneous rocks such as diorite, syenite, and andesite. It characteristically occurs in metamorphic rocks of granulite to amphibolite facies commonly exhibiting antiperthite texture. It also occurs as detrital grains in sedimentary rocks.
A sample of andesite (dark groundmass) with amygdaloidal vesicles filled with zeolite. Diameter of view is 8 cm. Adakite – Volcanic rock type; Andesite – Type of volcanic rock; Alkali feldspar granite – Type of igneous rock rich in alkali feldspar; Anorthosite – Mafic intrusive igneous rock composed predominantly of plagioclase
The tholeiitic magma series (/ ˌ θ oʊ l eɪ ˈ ɪ t ɪ k /) is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma into a more evolved, silica rich end member.
Mohs hardness of materials (data page) Vickers hardness test; Brinell scale This page was last edited on ...
Icelandite is a type of volcanic rock, an andesite that is enriched in iron but deficient in aluminium (< 16.5% Al 2 O 3). [1] [2] Icelandites are between rhyodacite and tholeiitic basalt in composition and contain andesine, hypersthene and augite, with a silica (SiO 2) content greater than 60%. [3] Icelandite is field O2 in the TAS classification.
Lapis Lacedaemonius (Latin: stone from Lacedaemon), also known as Spartan basalt, [1] is a form of andesite or volcanic rock known today only from a single source in the village of Krokees on the Peloponnese in Greece. [2] [3] In addition, ancient sources mention a quarry of lapis Lacedaemonius in Taygetus. [4]
Hornblende is a common constituent of many igneous and metamorphic rocks such as granite, syenite, diorite, gabbro, basalt, andesite, gneiss, and schist. It crystallizes in preference to pyroxene minerals from cooler magma that is richer in silica and water. [13]