Tremolite - Ca2(Mg,Fe2+)5[Si8O22](OH,F)2

Named in 1789 by Johann Georg Albrecht Höpfner for the Tremola Valley (Val Tremola), Central St Gotthard Massif, Tessin, Switzerland. Tremolite and actinolite are two very similar minerals that form a series with each other and essentially share the same chemical formula. Tremolite has a greater presence of magnesium over iron, whereas actinolite has a greater presence of iron over magnesium. Tremolite is a relatively common mineral in some metamorphic rocks. It occurs from the conversion of dolomite, silica and water into tremolite, calcite and carbon dioxide by way of the following reaction:

5CaMg(CO3)2 (dolomite) + 8SiO2 + H2O → Ca2Mg5Si8O22(OH)2 (tremolite) + 3CaCO3 (calcite) + 7CO2

Tremolite occurs as a result of contact metamorphism of calcium and magnesium rich siliceous sedimentary rocks and in greenschist facies metamorphic rocks derived from ultramafic or magnesium carbonate bearing rocks.

Optical Properties:
• Form: Fibrous crystals.
• Relief: Medium.
• Color: Colourless to pale green.
• Interference colors: Medium-high and decreases with increasing Fe2+ content.
• Extintion: Oblique.

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White radiating tufts of acicular tremolite crystals. Turret, Chaffee County, Colorado, USA. From RRUFF.




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White radiating tufts of acicular tremolite crystals. Turret, Chaffee County, Colorado, USA. From RRUFF.




Bibliography



• Bucher, K., & Grapes, R. (2011). Petrogenesis of metamorphic rocks. Springer Science & Business Media.
• Fossen, H. (2016). Structural geology. Cambridge University Press.
• Howie, R. A., Zussman, J., & Deer, W. (1992). An introduction to the rock-forming minerals (p. 696). Longman.
• Passchier, Cees W., Trouw, Rudolph A. J: Microtectonics (2005).
• Philpotts, A., & Ague, J. (2009). Principles of igneous and metamorphic petrology. Cambridge University Press.
• 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.
• Vernon, R. H. (2018). A practical guide to rock microstructure. Cambridge university press.


Photo
tremoliteelba(10).jpg

Acicular tremolite crystals in an altered peridotite. Elba Island (Italy). XPL image, 10x (Field of view = 7mm)		 tremoliteelba(11).jpg

Acicular tremolite crystals in an altered peridotite. Elba Island (Italy). XPL image, 10x (Field of view = 7mm)		 tremoliteelba(12).jpg

Acicular tremolite crystals in an altered peridotite. Elba Island (Italy). XPL image, 10x (Field of view = 7mm)
tremoliteelba(13).jpg

Acicular tremolite crystals in an altered peridotite. Elba Island (Italy). XPL image, 10x (Field of view = 7mm)		 tremoliteelba(15).jpg

Acicular tremolite crystals in an altered peridotite. Elba Island (Italy). PPL image, 10x (Field of view = 7mm)		 tremoliteelba(16).jpg

Acicular tremolite crystals in an altered peridotite. Elba Island (Italy). XPL image, 10x (Field of view = 7mm)
tremoliteelba(17).jpg

Acicular tremolite crystals in an altered peridotite. Elba Island (Italy). XPL image, 10x (Field of view = 7mm)		 tremoliteelba(18).jpg

Acicular tremolite crystals in an altered peridotite. Elba Island (Italy). XPL image, 10x (Field of view = 7mm)		 tremoliteelba(19).jpg

Acicular tremolite crystals in an altered peridotite. Elba Island (Italy). XPL image, 10x (Field of view = 7mm)
peridotitetremolitica(2).jpg

Acicular tremolite crystals in an altered peridotite. XPL image, 10x (Field of view = 7mm)		 peridotitetremolitica(3).jpg

Acicular, colorless, tremolite crystals in an altered peridotite. PPL image, 10x (Field of view = 7mm)		 peridotitetremolitica(4).jpg

Acicular tremolite crystals in an altered peridotite. XPL image, 10x (Field of view = 7mm)
peridotitetremolitica(5).jpg

Acicular, colorless, tremolite crystals in an altered peridotite. PPL image, 2x (Field of view = 7mm)		 peridotitetremolitica(6).jpg

Acicular tremolite crystals in an altered peridotite. XPL image, 2x (Field of view = 7mm)		 peridotitetremolitica(7).jpg

Acicular tremolite crystals in an altered peridotite. XPL image, 2x (Field of view = 7mm)
peridotitetremolitica(8).jpg

Acicular, colorless, tremolite crystals in an altered peridotite. PPL image, 10x (Field of view = 2mm)		 peridotitetremolitica(9).jpg

Acicular tremolite crystals in an altered peridotite. XPL image, 10x (Field of view = 2mm)		 peridotitetremolitica(10).jpg

Acicular, colorless, tremolite crystals on relict pyroxene in an altered peridotite. PPL image, 2x (Field of view = 7mm)
peridotitetremolitica(11).jpg

Acicular tremolite crystals on relict pyroxene in an altered peridotite. XPL image, 2x (Field of view = 7mm)		 peridotitetremolitica(12).jpg

Acicular tremolite crystals in an altered peridotite. XPL image, 10x (Field of view = 2mm)		 peridotitetremolitica(13).jpg

Acicular tremolite crystals in an altered peridotite. XPL image, 10x (Field of view = 2mm)
peridotitetremolitica(14).jpg

Acicular, colorless, tremolite crystals in an altered peridotite. PPL image, 10x (Field of view = 2mm)		 peridotitetremolitica(15).jpg

Acicular tremolite crystals in an altered peridotite. XPL image, 10x (Field of view = 2mm)		 peridotitetremolitica(16).jpg

Acicular tremolite crystals in an altered peridotite. XPL image, 10x (Field of view = 2mm)
peridotitetremolitica(17).jpg

Acicular, colorless, tremolite crystals in an altered peridotite. PPL image, 10x (Field of view = 2mm)		 peridotitetremolitica(18).jpg

Acicular tremolite crystals in an altered peridotite. XPL image, 10x (Field of view = 2mm)		 peridotitetremolitica(19).jpg

Acicular, colorless, tremolite crystals in an altered peridotite. PPL image, 10x (Field of view = 2mm)
peridotitetremolitica(20).jpg

Acicular tremolite crystals in an altered peridotite. XPL image, 10x (Field of view = 2mm)		 peridotitetremolitica(21).jpg

Acicular tremolite crystals in an altered peridotite. XPL image, 10x (Field of view = 2mm)		 tremolite(5000).jpg

Acicular, colorless, tremolite crystals in an altered peridotite. PPL image, 10x (Field of view = 2mm)
peridotitetremolitica1502(1).jpg

Acicular tremolite crystals (with high interference colors) in an altered peridotite. XPL image, 2x (Field of view = 7mm)		 peridotitetremolitica1502(2).jpg

Acicular tremolite crystals (with high interference colors) in an altered peridotite. XPL image, 2x (Field of view = 7mm)		 peridotitetremolitica1502(3).jpg

Acicular tremolite crystals (with high interference colors) in an altered peridotite. XPL image, 2x (Field of view = 7mm)
peridotitetremolitica1502(4).jpg

Acicular tremolite crystals (with high interference colors) in an altered peridotite. XPL image, 2x (Field of view = 7mm)		 peridotitetremolitica1502(5).jpg

Acicular tremolite crystals (with high interference colors) in an altered peridotite. XPL image, 10x (Field of view = 2mm)		 peridotitetremolitica1502(6).jpg

Acicular tremolite crystals (with high interference colors) in an altered peridotite. XPL image, 10x (Field of view = 2mm)
tremolite01844(1).jpg

Acicular tremolite crystals (with high interference colors). XPL image, 2x (Field of view = 7mm)		 tremolite01844(2).jpg

Acicular tremolite crystals (with high interference colors). XPL image, 2x (Field of view = 7mm)		 tremolite01844(4).jpg

Acicular tremolite crystals (colorless). PPL image, 2x (Field of view = 7mm)
tremolite01844(5).jpg

Acicular tremolite crystals (with high interference colors). XPL image, 2x (Field of view = 7mm)		 tremolite01844(6).jpg

Acicular tremolite crystals (with high interference colors). XPL image, 2x (Field of view = 7mm)		 tremolite01844(7).jpg

Acicular tremolite crystals (with high interference colors). XPL image, 2x (Field of view = 7mm)
tremolite01844(8).jpg

Acicular tremolite crystals (with high interference colors). XPL image, 2x (Field of view = 7mm)		 tremolite01844(9).jpg

Acicular tremolite crystals (colorless). PPL image, 2x (Field of view = 7mm)		 tremolite01844(10).jpg

Acicular tremolite crystals (with high interference colors). XPL image, 2x (Field of view = 7mm)
tremolite01844(11).jpg

Acicular tremolite crystals (with high interference colors). XPL image, 2x (Field of view = 7mm)		 tremolite01844(12).jpg

Acicular tremolite crystals (with high interference colors). XPL image, 2x (Field of view = 7mm)		 tremolite01844(13).jpg

Acicular tremolite crystals (colorless). PPL image, 2x (Field of view = 7mm)
tremolite01844(14).jpg

Acicular tremolite crystals (with high interference colors). XPL image, 2x (Field of view = 7mm)		 tremolite01844(15).jpg

Acicular tremolite crystals (with high interference colors). XPL image, 2x (Field of view = 7mm)		 tremolite01844(16).jpg

Acicular tremolite crystals (with high interference colors). XPL image, 2x (Field of view = 7mm)
tremolite(salarioli)(1).jpg

tremolite crystals (with high interference colors). Salarioli, Piedmont, Italy. XPL image, 2x (Field of view = 7mm)		 tremolite(salarioli)(2).jpg

tremolite crystals (with high interference colors). Salarioli, Piedmont, Italy. XPL image, 2x (Field of view = 7mm)		 tremolite(salarioli)(4).jpg

tremolite crystals (with high interference colors). Salarioli, Piedmont, Italy. XPL image, 2x (Field of view = 7mm)
tremolite(salarioli)(5).jpg

tremolite crystals (with high interference colors). Salarioli, Piedmont, Italy. XPL image, 2x (Field of view = 7mm)		 tremolite(salarioli)(8).jpg

tremolite crystals (with high interference colors). Salarioli, Piedmont, Italy. XPL image, 2x (Field of view = 7mm)		 tremolite(salarioli)(9).jpg

Basal sections of tremolite crystals. Salarioli, Piedmont, Italy. PPL image, 2x (Field of view = 7mm)
tremolite(salarioli)(10).jpg

Basal sections of tremolite crystals. Salarioli, Piedmont, Italy. XPL image, 2x (Field of view = 7mm)		 tremolite(salarioli)(11).jpg

tremolite crystals (with high interference colors). Salarioli, Piedmont, Italy. XPL image, 2x (Field of view = 7mm)		 tremolite(salarioli)(13).jpg

tremolite crystals (with high interference colors). Salarioli, Piedmont, Italy. XPL image, 2x (Field of view = 7mm)