An amphibolite boulder in the Botanical Gardens of Charles University, Prague, Czech Republic.
Composition
Amphiboles, such as hornblende and actinolite, often with plagioclase.
Physical Characteristics
Fabric
Schistose
Relationships
Protoliths
Mafics, such as basalt
Amphibolite from Cape Cod, MassachusettsGarnet bearing amphibolite from Val di Fleres, Italy
Amphibolite (/æmˈfɪbəlaɪt/) is a metamorphic rock that contains amphibole, especially hornblende and actinolite, as well as plagioclase feldspar, but with little or no quartz. It is typically dark-colored and dense, with a weakly foliated or schistose (flaky) structure. The small flakes of black and white in the rock often give it a salt-and-pepper appearance.
Amphibolite frequently forms by metamorphism of mafic igneous rocks, such as basalt. However, because metamorphism creates minerals entirely based upon the chemistry of the protolith, certain 'dirty marls' and volcanic sediments may also metamorphose to an amphibolite assemblage. Deposits containing dolomite and siderite also readily yield amphibolite (tremolite-schist, grunerite-schist, and others) especially where there has been a certain amount of contact metamorphism by adjacent granitic masses. Metamorphosed basalt (metabasalt) creates ortho-amphibolite and other chemically appropriate lithologies create para-amphibolite.
Although tremolite is a metamorphic amphibole, it is most commonly derived from highly metamorphosed ultramafic rocks, and thus tremolite-talc schist is not generally considered a variety of amphibolite. A holocrystalline plutonic igneous rock composed primarily of hornblende amphibole is called a hornblendite, which is usually a crystal cumulate rock. Igneous rocks with greater than 90% amphiboles, which have a feldspar groundmass, may be lamprophyres.
Amphibolite (/æmˈfɪbəlaɪt/) is a metamorphic rock that contains amphibole, especially hornblende and actinolite, as well as plagioclase feldspar, but...
Amphibolite Point (60°41′S 45°21′W / 60.683°S 45.350°W / -60.683; -45.350) is a conspicuous, pyramidal point 1.5 nautical miles (3 km) northwest of...
protolith, so that (for example) the amphibolite facies of a marble will not be identical with the amphibolite facies of a pelite. However, the facies...
protolith, so that (for example) the amphibolite facies of a marble will not be identical with the amphibolite facies of a pellite. However, the facies...
Mn-garnet (spessartine) In Si-rich dolomite rocks: dolomite + quartz The amphibolite facies is a facies of medium pressure and average to high temperature...
the world's largest garnets. The rock that holds these garnets, garnet amphibolite, is sometimes referred to as 'black ore' or 'dark ore.' This rock formation...
characteristic of areas of regional metamorphism that reaches the middle amphibolite to granulite metamorphic facies. In other words, the rock was metamorphosed...
containing up to 50% albite and Al2O3-rich pyroxenes. Transition between amphibolite and granulite facies is defined by these reaction isograds: amphibole...
Scourie dykes form amphibolite sheets within the reworked gneisses. The original mineralogy of the dykes is also changed to an amphibolite facies assemblage...
compared to the dark green of common amphibolites, giving it the nickname "faux-amphibolite". The cummingtonite amphibolite displays gneissic foliation, with...
uncarbonated amphibolite facies serpentinites Magnesite, and rarely dolomite in association with amphibolitic compositions At amphibolite facies, the diopside-in...
which are only safely accessible at low tide. Sark is made up mainly of amphibolite and granite gneiss rocks, intruded by igneous magma sheets called quartz...
the corresponding pyroxenes. Amphiboles are the primary constituent of amphibolites. Like pyroxenes, amphiboles are classified as inosilicate (chain silicate)...
5 billion years ago), these metamorphic rocks include gneiss, schist and amphibolites. Metamorphic rocks are the most common types found in the northern and...
temperature and pressure of metamorphism, these may include greenschist, amphibolite, or eclogite. Basalts are important rocks within metamorphic regions...
interlayered amphibolite and felsic gneiss; 5) felsic gneiss with scattered biotite +/-magnetite, garnet, and hornblende; 6) interbedded amphibolite and white...
Geologic map of Hispaniola. Mzb are Mesozoic amphibolites and associated metasedimentary rocks, Ki are Cretaceous plutons, Kv are Cretaceous volcanic rocks...
composed almost entirely of labradorite. It also is found in metamorphic amphibolites and as a detrital component of some sediments. Common mineral associates...
geomorphic region. The island's bedrock consists of metasedimentary amphibolite, which dips towards the east at about 35 degrees. The island is contained...
include sub-amphibolite facies. If burial continues along Barrovian Sequence metamorphic trajectories, greenschist facies gives rise to amphibolite facies...
inselbergs are commonly made of granite, sometimes of gneiss and never of amphibolite or volcanic rock. Protruding quartzite hills tend to form ridges rather...
are commonly made of granite rock, sometimes of gneiss and never of amphibolite or volcanic rock. According to Ollier protuding quartzite hills tend...
andesite. It characteristically occurs in metamorphic rocks of granulite to amphibolite facies commonly exhibiting antiperthite texture. It also occurs as detrital...
years old. The rocks have experienced multiple metamorphic events at amphibolite or granulite conditions, resulting in often complete destruction of original...
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