Latite

Latite: A term originally proposed for a rock which chemically lies between trachyte and andesite, but later used as a volcanic rock composed of approximately equal amounts of alkali feldspar and sodic plagioclase, i.e. the volcanic equivalent of monzonite. Now defined chemically as the potassic variety of trachyandesite in TAS. The term Latite derives from Latium an Italian region (central Italy). In latites quartz is less than five percent, when quartz content is greater than five percent the rock is classified as quartz latite. Biotite, hornblende, pyroxene and scarce olivine are common accessory minerals.

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Latite. Boxberg, Hocheifel, Germany. From Wikipedia.

Porphyritic latite. Colorado, USA. From James St. John.

Latite. Colli Euganei, Italy. From Euganeamente.

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
Sanidine, plagioclase, pyroxene (green) and altered olivine crystals in a Latite from Bolsena lake (Latium, Italy). PPL image, 2x (Field of view = 7mm)	Sanidine, plagioclase, pyroxene (green) and altered olivine crystals in a Latite from Bolsena lake (Latium, Italy). PPL image, 2x (Field of view = 7mm)	Sanidine, plagioclase and altered olivine crystals in a Latite from Bolsena lake (Latium, Italy). PPL image, 2x (Field of view = 7mm)
Sanidine, plagioclase and altered olivine crystals in a Latite from Bolsena lake (Latium, Italy). XPL image, 2x (Field of view = 7mm)	Biotite, sanidine, plagioclase and pyroxene (green) in a Latite from Bolsena lake (Latium, Italy). PPL image, 2x (Field of view = 7mm)	Biotite, sanidine, plagioclase and pyroxene (green) in a Latite from Bolsena lake (Latium, Italy). PPL image, 2x (Field of view = 7mm)
Sanidine and pyroxene in a Latite from Bolsena lake (Latium, Italy). XPL image, 2x (Field of view = 7mm)	Sanidine and pyroxene in a Latite from Bolsena lake (Latium, Italy). XPL image, 2x (Field of view = 7mm)	Sanidine and pyroxene in a Latite from Bolsena lake (Latium, Italy). XPL image, 2x (Field of view = 7mm)
Biotite, plagioclase and pyroxene + plagioclase cluster in a Latite from Bolsena lake (Latium, Italy). PPL image, 2x (Field of view = 7mm)	Biotite, plagioclase and pyroxene + plagioclase cluster in a Latite from Bolsena lake (Latium, Italy). XPL image, 2x (Field of view = 7mm)	Pyroxene + plagioclase cluster in a Latite from Bolsena lake (Latium, Italy). PPL image, 2x (Field of view = 7mm)
Pyroxene + plagioclase cluster in a Latite from Bolsena lake (Latium, Italy). XPL image, 2x (Field of view = 7mm)	Biotite, plagioclase and pyroxene + plagioclase cluster in a Latite from Bolsena lake (Latium, Italy). XPL image, 2x (Field of view = 7mm)	Pyroxene + plagioclase cluster in a Latite from Bolsena lake (Latium, Italy). XPL image, 2x (Field of view = 7mm)