prehnite
prehnite A hydrated silicate and member of the phyllosilicates (sheet silicates) with composition Ca2Al[Si3AlO10]OH2; sp. gr. 2.9; hardness 6.0; colourless, white, or green; tabular or in granular aggregates; has a layered structure similar to the micas; occurs in association with the zeolites infilling cavities in basic igneous rocks and in contact metamorphosed (see THERMAL METAMORPHISM) limestones. See also PREHNITE-PUMPELLYITE FACIES.
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Natrolite , natrolite Member of the zeolite group of minerals, with the formula Na2Al2Si3O10.2H2O; sp. gr. 2.2; hardness 5.0; white; massive, fibrous, or crystal… Wollastonite , enstatite (En) An important orthorhombic pyroxene (orthopyroxene, or opx) Mg2Si2O6 and end-member of an isomorphous series, the other end-member bein… Epidote , Epidote
epidote (pistacite) A rock-forming mineral Ca2(Al2Fe3+)Si3O12(OH) and a member of the epidote group of minerals, which includes zoisite, clin… diabase , dolerite (diabase, microgabbro) A dark-coloured, medium-grained igneous rock which contains plagioclase feldspar of labradorite composition and pyrox… Corundum , corundum Mineral, Al2O3; sp. gr. 3.9–4.1; hardness 9; trigonal; the two main varieties blue and green, but can be yellow, or brown to almost black, a… Hornfels , Hornfels is a fine-textured metamorphic rock formed by contact metamorphism . Contact metamorphism occurs when a mass of hot magma intrudes into pree…
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prehnite