Plagioclase-bearing 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.

Bibliography

• Cox et al. (1979): The Interpretation of Igneous Rocks, George Allen and Unwin, London.
• Howie, R. A., Zussman, J., & Deer, W. (1992). An introduction to the rock-forming minerals (p. 696). Longman.
• Le Maitre, R. W., Streckeisen, A., Zanettin, B., Le Bas, M. J., Bonin, B., Bateman, P., & Lameyre, J. (2002). Igneous rocks. A classification and glossary of terms, 2. Cambridge University Press.
• Middlemost, E. A. (1986). Magmas and magmatic rocks: an introduction to igneous petrology.
• Shelley, D. (1993). Igneous and metamorphic rocks under the microscope: classification, textures, microstructures and mineral preferred-orientations.
• Vernon, R. H. & Clarke, G. L. (2008): Principles of Metamorphic Petrology. Cambridge University Press.

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