Fundamental Minerals

Sialic Minerals

Feldspars

Feldspathoids

Quartz

Femic Minerals

Spodumene

Accessory Minerals

Rare Accessory

Alteration Products

Microstructures

Rocks

Jacupiranga complex

Monzonite

Monzonite was originally named after the Monzoni range in Val di Fassa (Trento Province, Italy) where it is abundant. Monzonite is a plutonic igneous rock intermediate in composition between syenite and diorite. Monzonite contains less quartz and more plagioclase than granite. It is composed of approximately equal amounts of plagioclase and alkali feldspar, with less than 5% quartz by weight. It may contain minor amounts of hornblende, biotite and other minerals. If quartz constitutes greater than 5%, the rock is termed a quartz monzonite. Latite or trachyandesite are the approximate volcanic equivalents of monzonite. Monzonite is a relatively uncommon rock type. It usually does not form its own plutons. Monzonitic magma most likely forms only a part of a generally more acidic (granitic) intrusions. A great variety of names (now all obsolete) have been attributed in time to these rocks:

Windsorite: Obsolete name for a light-colored quartz-monzonite aplite with minor amount of biotite. named by Daly in 1903 after Windsor, Vermont, USA
Ukrainite: A local name for Quartz-monzonite; from type locality in Ukraine
Masanite: A Quartz-monzonite containing phenocrysts of zoned plagiolcase and corroded quartz in a granophyric groundmass. Name given by Koto (1909) from Masan-po, Korea
Sörkedalite: A local name for a variety of olivine monzodiorite consisting of abundant antiperthitic andesine, mantled by anorthoclase, and by olivine; minor amount of clino-pyroxene and biotite may be present. From Sorkedal, Oslo, Norway.
Larvikite: A variety of augite syenite or monzonite consisting of rhombshaped ternary feldspars (with a distinctive schiller), from Larvik, Oslo Igneous Province, Norway.
Vallevarite: An obsolete local name for a variety of anorthosite, consisting essentially of andesine and microcline antiperthite with minor diopside and biotite. From Vallevara, Sweden.
Amherstite: A leucocratic variety of quartz belonging to the charnockitic rock series. The rock consists essentially of andesine-microcline antiperthite with minor quartz and hypersthene. From Amherst County, Virginia,USA.
Kjelsaite: A local name given to a plagioclase-rich larvikite which is a variety of augite syenite or monzonite. From Kjelsas, Oslo district, Norway.

Monzonite sample: plagioclase (white), alkali feldspar (pink) and biotite (dark). France. From Sand Atlas

Monzoni massif, Val di Fassa, Italy. From veramontagna

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
Orthoclase (altered by sericite), biotie (brown), magnetite (black) and pyroxene crystals in a monzonite from Monzoni massif, Italy. PPL image, 2x (Field of view = 7mm)	Orthoclase (I order gray), biotie, magnetite (black) and pyroxene (high interference colors) crystals in a monzonite from Monzoni massif, Italy. XPL image, 2x (Field of view = 7mm)	Orthoclase (altered by sericite), biotie (brown), magnetite (black) and pyroxene crystals in a monzonite from Monzoni massif, Italy. PPL image, 2x (Field of view = 7mm)
Orthoclase (I order gray), biotie, magnetite (black) and pyroxene (high interference colors) crystals in a monzonite from Monzoni massif, Italy. XPL image, 2x (Field of view = 7mm)	Orthoclase (altered by sericite), biotie (brown), magnetite (black) and pyroxene crystals in a monzonite from Monzoni massif, Italy. PPL image, 2x (Field of view = 7mm)	Orthoclase (I order gray), biotie, magnetite (black) and pyroxene (high interference colors) crystals in a monzonite from Monzoni massif, Italy. XPL image, 2x (Field of view = 7mm)
Biotie (brown), magnetite (black) and pyroxene crystals in a monzonite from Monzoni massif, Italy. PPL image, 2x (Field of view = 7mm)	Biotie, magnetite (black) and pyroxene (high interference colors) crystals in a monzonite from Monzoni massif, Italy. XPL image, 2x (Field of view = 7mm)	Orthoclase (altered by sericite), biotie (brown), magnetite (black) and pyroxene crystals in a monzonite from Monzoni massif, Italy. PPL image, 2x (Field of view = 7mm)
Orthoclase (I order gray), biotie, magnetite (black) and pyroxene (high interference colors) crystals in a monzonite from Monzoni massif, Italy. XPL image, 2x (Field of view = 7mm)	Biotie, magnetite (black) and pyroxene (high interference colors) crystals in a monzonite from Monzoni massif, Italy. XPL image, 2x (Field of view = 7mm)	Orthoclase (altered by sericite), biotie (brown), magnetite (black) and pyroxene crystals in a monzonite from Monzoni massif, Italy. PPL image, 2x (Field of view = 7mm)
Orthoclase (I order gray), biotie, magnetite (black) and pyroxene (high interference colors) crystals in a monzonite from Monzoni massif, Italy. XPL image, 2x (Field of view = 7mm)	Orthoclase (altered by sericite) and with altered olivine inclusions, biotie (brown), magnetite (black) and pyroxene crystals in a monzonite from Monzoni massif, Italy. PPL image, 2x (Field of view = 7mm)	Orthoclase (I order gray) and with altered olivine inclusions, biotie, magnetite (black) and pyroxene (high interference colors) crystals in a monzonite from Monzoni massif, Italy. XPL image, 2x (Field of view = 7mm)
Orthoclase (altered by sericite), biotie (brown), magnetite (black) and pyroxene crystals in a monzonite from Monzoni massif, Italy. PPL image, 2x (Field of view = 7mm)	Orthoclase (I order gray), biotie, magnetite (black) and pyroxene (high interference colors) crystals in a monzonite from Monzoni massif, Italy. XPL image, 2x (Field of view = 7mm)	Orthoclase (altered by sericite), biotie (brown), magnetite (black) and pyroxene crystals in a monzonite from Monzoni massif, Italy. PPL image, 2x (Field of view = 7mm)
concentric inclusion in a pyroxene crystal in a monzonite from Monzoni massif, Italy. PPL image, 2x (Field of view = 7mm)	concentric inclusion in a pyroxene (high interference colors) crystal in a monzonite from Monzoni massif, Italy. XPL image, 2x (Field of view = 7mm)	concentric inclusion in a pyroxene (high interference colors) crystal in a monzonite from Monzoni massif, Italy. XPL image, 10x (Field of view = 2mm)
Orthoclase (I order gray), plagioclase (I order gray with polysynthetic twinning) and clinopyroxene (high interference colors). XPL image, 2x (Field of view = 7mm)	Orthoclase, plagioclase (both colorles) and clinopyroxene (high relief, pale gray-green). PPL image, 2x (Field of view = 7mm)	Orthoclase (I order gray), plagioclase (I order gray with polysynthetic twinning) and clinopyroxene (high interference colors). XPL image, 2x (Field of view = 7mm)
Orthoclase, plagioclase (both colorles), hornblende (green) and clinopyroxene (high relief, pale gray-green). PPL image, 2x (Field of view = 7mm)	Orthoclase (I order gray), plagioclase (I order gray with polysynthetic twinning) and clinopyroxene (high interference colors). XPL image, 2x (Field of view = 7mm)	Orthoclase (I order gray), plagioclase (I order gray with polysynthetic twinning) and clinopyroxene (high interference colors). XPL image, 2x (Field of view = 7mm)
Orthoclase (I order gray), plagioclase (I order gray with polysynthetic twinning) and clinopyroxene (high interference colors). XPL image, 2x (Field of view = 7mm)	Zoned plagioclase. XPL image, 2x (Field of view = 7mm)	Zoned plagioclase. XPL image, 2x (Field of view = 7mm)
Sericitized plagioclase and pyroxene. XPL image, 2x (Field of view = 7mm)	Sericitized plagioclase and pyroxene. XPL image, 2x (Field of view = 7mm)	Sericitized plagioclase and pyroxene. XPL image, 2x (Field of view = 7mm)
Sericitized plagioclase and pyroxene. XPL image, 2x (Field of view = 7mm)	Sericitized plagioclase and pyroxene. XPL image, 2x (Field of view = 7mm)	Sericitized plagioclase and pyroxene. XPL image, 2x (Field of view = 7mm)