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An aphanitic volcanic sand grain, with fine-grained groundmass, as seen through a petrographic microscope Aphanites (adj. aphanitic ; from Ancient Greek αφανης (aphanḗs) 'invisible') are igneous rocks that are so fine-grained that their component mineral crystals are not visible to the naked eye [ 2 ] (in contrast to phanerites , in ...
This page is intended to be a list of rock textural and morphological ... see igneous texture; ... Quench textures; see obsidian, tachylyte or aphanitic; R ...
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 with few or no crystals. Examples include obsidian.
Pages in category "Aphanitic rocks" The following 12 pages are in this category, out of 12 total. ... Phenotype (igneous petrology) Picrite basalt; R. Rhyodacite
Tephriphonolite – Type of igneous rock – A volcanic rock with a composition between phonotephrite and phonolite; Tephrite – Igneous, volcanic rock – A silica-undersaturated volcanic rock; Tonalite – Igneous rock – A plagioclase-dominant granitoid; Trachyandesite – Extrusive igneous rock – An alkaline intermediate volcanic rock
Basalt (UK: / ˈ b æ s ɒ l t,-ɔː l t,-əl t /; [1] [2] US: / b ə ˈ s ɔː l t, ˈ b eɪ s ɔː l t /) [3] is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon.
"Imperial Porphyry" from the Red Sea Mountains of Egypt A waterworn cobble of porphyry Rhyolite porphyry from Colorado; scale bar in lower left is 1 cm (0.39 in). Porphyry (/ ˈ p ɔːr f ə r i / POR-fə-ree) is any of various granites or igneous rocks with coarse-grained crystals such as feldspar or quartz dispersed in a fine-grained silicate-rich, generally aphanitic matrix or groundmass.
Igneous rock (igneous from Latin igneus 'fiery'), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet's mantle or crust.