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The changes that occur are greatest wherever the magma comes into contact with the rock because the temperatures are highest at this boundary and decrease with distance from it. Around the igneous rock that forms from the cooling magma is a metamorphosed zone called a contact aureole. Aureoles may show all degrees of metamorphism from the ...
In metamorphosed sandstone, recrystallization of the original quartz sand grains results in very compact quartzite, also known as metaquartzite, in which the often larger quartz crystals are interlocked. [14] Both high temperatures and pressures contribute to recrystallization.
Psammite (Greek: psammitēs "(made) from sand", from psammos "sand") [1] is a general term for sandstone.It is equivalent to the Latin-derived term arenite [2] [3] and is commonly used in various publications to describe a metamorphosed sedimentary rock with a dominantly sandstone protolith. [4]
Quartzite can have a grainy, glassy, sandpaper-like surface. Quartzite is a hard, non-foliated metamorphic rock which was originally pure quartz sandstone. [1] [2] Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts.
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains, cemented together by another mineral. Sandstones comprise about 20–25% of all sedimentary rocks. [1] Most sandstone is composed of quartz or feldspar, because they are the most resistant minerals to the weathering processes at the Earth's ...
Arenite (from the Latin arena, "sand") [1] is a sedimentary clastic rock with sand grain size between 0.0625 mm (0.00245 in) and 2 mm (0.08 in) and containing less than 15% matrix. [2] The related adjective is arenaceous. The equivalent Greek-derived term is psammite, though this is more commonly used for metamorphosed sediments.
Greywacke or graywacke (German grauwacke, signifying a grey, earthy rock) is a variety of sandstone generally characterized by its hardness (6–7 on Mohs scale), dark color, and poorly sorted angular grains of quartz, feldspar, and small rock fragments or sand-size lithic fragments set in a compact, clay-fine matrix.
Evaporite – Water-soluble mineral deposit formed by evaporation from an aqueous solution; Flint – Cryptocrystalline form of the mineral quartz; Geyserite – Form of opaline silica often found around hot springs and geysers; Greywacke – Sandstone with angular grains in a clay-fine matrix; Gritstone – Hard, coarse-grained, siliceous ...