Fundamental Minerals

Sialic Minerals

Feldspars

Feldspathoids

Quartz

Femic Minerals

Spodumene

Accessory Minerals

Rare Accessory

Alteration Products

Microstructures

Rocks

Jacupiranga complex

Apatite - Ca₅(PO₄)₂[F, OH, Cl]

Apatite structure is characterized by phosphate oxyanion linked by Ca²⁺ cations to forma hexagonal frame-work with F^- anions lying at the corners of hexagonal cell and coordinated by three Ca^2- cations. Composition of the apatite minerals is highly variable and there is a complete solid solution between three end-members, fluoroapatite Ca₅(PO₄)₃F, chloroapatite Ca₅(PO₄)₃Cl and hydroxylapatite Ca₅(PO₄)OH. The dominant anion (F,Cl,OH) determinate the Apatite variety. Apatite is a very common early-formed accessory mineral in nearly all type of igneous rocks. Apatite is also concentrated by late magmatic segregation, and it appears in granite pegmatite.

Optical Properties:

• Form: Tiny euhedral prismatic crystals elongated on c, with exagonal basal section and rectangular to acicular prismatic section.
• Relief: High.
• Color: Colorless.
• Interference Colors: weak.
• cleavage: Poor parallel to (001).

Green apatite crystals in a carbonatite. Siilinjärvi, Finland. From sand atlas.

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
Pyroxene in basal section (with colorless apatite inclusions) in a xenolith from Vulsini volcano, Italy. PPL image, 2x (Field of view = 7mm)	Pyroxene in basal section (with colorless apatite inclusions) in a xenolith from Vulsini volcano, Italy. PPL image, 10x (Field of view = 2mm)	Pyroxene in basal section (with colorless apatite inclusions) in a xenolith from Vulsini volcano, Italy. PPL image, 10x (Field of view = 2mm)
Calcite, biotite and apatite (I order gray) crystals in a sövite from Sào Vicente island, Cape Verde. XPL image, 1x (Field of view = 9mm)	Calcite and apatite (high relief, colorless) crystals in a sövite from Sào Vicente island, Cape Verde. PPL image, 1x (Field of view = 9mm)	Calcite and apatite (I order gray) crystals in a sövite from Sào Vicente island, Cape Verde. XPL image, 1x (Field of view = 9mm)
Calcite and apatite (I order gray) crystals in a sövite from Sào Vicente island, Cape Verde. XPL image, 2x (Field of view = 7mm)	Calcite and apatite (high relief, colorless) crystals in a sövite from Sào Vicente island, Cape Verde. PPL image, 2x (Field of view = 7mm)	Calcite and apatite (I order gray) crystals in a sövite from Sào Vicente island, Cape Verde. XPL image, 2x (Field of view = 7mm)
Phlogopite (brown), calcite, apatite (high relief, colorless) and magnetite (black) crystals in a carbonatite from Sokli carbonatite complex, Finland. PPL image, 1x (Field of view = 9mm)	Phlogopite (high birefringence), calcite, apatite (I order gray) and magnetite crystals in a carbonatite from Sokli carbonatite complex, Finland. XPL image, 1x (Field of view = 9mm)	Phlogopite (brown), calcite, apatite (high relief, colorless) and magnetite (black) crystals in a carbonatite from Sokli carbonatite complex, Finland. PPL image, 1x (Field of view = 9mm)
Apatite crystals in biotite. PPL image, 2x (Field of view = 7mm)	Apatite crystals in biotite. PPL image, 2x (Field of view = 7mm)	Apatite crystals in biotite. PPL image, 2x (Field of view = 7mm)
Apatite crystals in biotite. PPL image, 2x (Field of view = 7mm)	Apatite crystals in biotite. PPL image, 2x (Field of view = 7mm)	Apatite crystals in biotite. PPL image, 2x (Field of view = 7mm)
Apatite crystals (hexagonal basal section) in augite. PPL image, 10x (Field of view = 2mm)	Apatite crystals (hexagonal basal section) in augite. PPL image, 10x (Field of view = 2mm)	Apatite crystals (hexagonal basal section) in augite. PPL image, 10x (Field of view = 2mm)
Apatite crystals (hexagonal basal section) in augite. PPL image, 10x (Field of view = 2mm)	Apatite crystals (hexagonal basal section) in augite. PPL image, 10x (Field of view = 2mm)	Apatite crystals (hexagonal basal section) in augite. XPL image, 10x (Field of view = 2mm)
Apatite crystals (hexagonal basal section) in augite. PPL image, 10x (Field of view = 2mm)	Apatite crystals (hexagonal basal section) in augite. PPL image, 10x (Field of view = 2mm)	Apatite crystals in augite. PPL image, 10x (Field of view = 2mm)
Apatite crystals in augite. XPL image, 10x (Field of view = 2mm)	Apatite crystals in augite. PPL image, 10x (Field of view = 2mm)	Apatite crystals in augite. PPL image, 10x (Field of view = 2mm)