Fluorite - CaF₂

Fluorite is a halide mineral with formula CaF₂; Named in 1797 by Carlo Antonio Galeani Napione from the Latin, fluere = "to flow" (for its use as a flux in steel and aluminum processing). The term fluorescence is derived from fluorite, which will often markedly exhibit this effect. The element fluorine also derives its name from fluorite, a major source for the element. The color of the fluorite has always been a matter of debate, but recent studies have shown that certain elements such as rare earths determine specific color:

Y = blue
Y + Ce = green-yellow
YO₂ = pink
O₃ = yellow
Sm²⁺ = green

Fluorite is a late-stage mineral in granite and other magmatic acid rocks; fluorite usually crystallize at low temperatures (around 500°C). in late-stage pneumatolitic or in skarn deposits fluorite occurs with cassiterite, calcite, sulphides and other minerals.

Optical properties:

• Form: Usually found as euhedhral crystals, usually cube, or octahedrons. Also massive.
• Relief: High.
• Color: Usually colorless.
• Cleavage: Perfect Octahedral; Four direction are distinctive and commonly produce fragments as trigonal pyramids or triangular shapes.
• Interference colors: Isotropic.

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
Colorless fluorite crystals (with octahedral cleavage) and green amphiboles. PPL image, 10x (Field of view = 2mm)	Colorless fluorite crystals (with octahedral cleavage) and green amphiboles. PPL image, 10x (Field of view = 2mm)	Colorless fluorite crystals (with octahedral cleavage). PPL image, 10x (Field of view = 2mm)
Colorless fluorite crystals (with octahedral cleavage) and green amphiboles. PPL image, 10x (Field of view = 2mm)	Colorless fluorite crystals (with octahedral cleavage) and green amphiboles. PPL image, 10x (Field of view = 2mm)	Colorless fluorite crystals (with octahedral cleavage) and green amphiboles. PPL image, 10x (Field of view = 2mm)
Colorless fluorite crystals (with octahedral cleavage) and green amphiboles. PPL image, 20x (Field of view = 1mm)	Colorless fluorite crystals (with octahedral cleavage) and green amphiboles. PPL image, 10x (Field of view = 2mm)	Colorless fluorite crystals (with octahedral cleavage) and green amphiboles. PPL image, 10x (Field of view = 2mm)
Colorless fluorite crystals (with octahedral cleavage) from Vesuvius. PPL image, 10x (Field of view = 2mm)	Colorless fluorite crystals (with octahedral cleavage) from Vesuvius. PPL image, 10x (Field of view = 2mm)	Colorless fluorite crystals (isotropic) from Vesuvius. PPL image, 10x (Field of view = 2mm)
Colorless fluorite crystals (with octahedral cleavage) from Vesuvius. PPL image, 10x (Field of view = 2mm)	Colorless fluorite crystals (isotropic) from Vesuvius. PPL image, 10x (Field of view = 2mm)	Colorless fluorite crystals (with octahedral cleavage) from Vesuvius. PPL image, 20x (Field of view = 1mm)
Colorless fluorite crystals (with octahedral cleavage) from Vesuvius. PPL image, 20x (Field of view = 1mm)	Colorless fluorite crystals (with octahedral cleavage) from Vesuvius. PPL image, 10x (Field of view = 2mm)	Colorless fluorite crystals (with octahedral cleavage) from Vesuvius. PPL image, 10x (Field of view = 2mm)

Metamorphic Minerals

Texture and Microstructure

Metamorphic Rocks

Fluorite - CaF2

Fluorite - CaF₂