Plagioclase-bearing Px Hornbelndite

A hornblendite is an ultramafic igneous rock dominated by hornblende. It is different from an amphibolite which is a amphibole and plagioclase dominated metamorphic rock. Horblendite is a rare rock most commonly associated with diorite, granite, gabbro and peridotite. They form as cumulates by settling of early crystallised hornblende in hydrous magmas, other related rocks such as hornblende gabbro and hornblende peridotite also form by accumulation. Hornblendites are also associated with Precambrian tonalite-trondhjemite-granodiorite series rocks.

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Ol-Px-Hbl Diagram for Ultramafic rocks. hornblendite field in blue




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Hornblendite samples




Bibliography



• Eric A.K.Middlemost (1985): Magmas and Magmatic Rocks. Longman, London
• Ron H. Vernon (2004): A pratical guide to rock microstructure. Cambridge editore
• K.G.Cox, J.D.Bell & R.J Pankhurst (1979): The interpretetion of igneous rocks. George Allen&Unwin editori.
• David Shelley (1983): Igneous and metamorphic rocks under the microscope. Campman & Hall editori


Photo
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Hornblende, Olivine and phlogopite. PPL image, 2x (Field of view = 7mm)/td>
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Hornblende, Olivine (rimmed by pyroxene) and phlogopite. PPL image, 2x (Field of view = 7mm)/td>
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Hornblende, Olivine (rimmed by pyroxene) and phlogopite. XPL image, 2x (Field of view = 7mm)/td>
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Hornblende, Olivine and phlogopite. PPL image, 2x (Field of view = 7mm)/td>
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Hornblende, Olivine (rimmed by pyroxene) and phlogopite. PPL image, 2x (Field of view = 7mm)/td>
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Hornblende, Olivine and phlogopite. XPL image, 2x (Field of view = 7mm)/td>
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Hornblende, Olivine and phlogopite. PPL image, 2x (Field of view = 7mm)/td>
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Olivine rimmed by pyroxene. PPL image, 2x (Field of view = 7mm)/td>
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Olivine rimmed by pyroxene. PPL image, 10x (Field of view = 2mm)/td>
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Olivine rimmed by pyroxene. PPL image, 10x (Field of view = 2mm)/td>
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Olivine rimmed by pyroxene. XPL image, 10x (Field of view = 2mm)/td>
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Hornblende, plagioclase and phlogopite. PPL image, 2x (Field of view = 7mm)/td>
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Hornblende, plagioclase and phlogopite. XPL image, 2x (Field of view = 7mm)/td>
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Hornblende, plagioclase and phlogopite. PPL image, 2x (Field of view = 7mm)/td>
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Hornblende, plagioclase and phlogopite. PPL image, 2x (Field of view = 7mm)/td>
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Hornblende, plagioclase and phlogopite. XPL image, 2x (Field of view = 7mm)/td>
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Poikilitic phlogopite with Hornblend inclusions. PPL image, 2x (Field of view = 7mm)/td>
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Poikilitic phlogopite with Hornblend inclusions. PPL image, 2x (Field of view = 7mm)/td>