Lazurite - Na6Ca2(Al6Si6O24)(SO4,S,S2,S3,Cl,OH)2

Lazurite, member of the sodalite group, is the blue component of the "gemstone" (or, more usually, decorative rock) Lapis Lazuli, which is a lazurite-calcite-pyrite rock that has been mined as a gem material for some 9.000 years. Lazurite was first described in 1890 for an occurrence in the Sar-e-Sang District, Koksha Valley, Badakhshan Province, Afghanistan. The name lazurite is derived from the term "lazaward", which means heaven in Arabic, alluding to its blue color. Lazurite occurs almost exclusively in massive form without any visible crystals. The exception is the historic occurrence of Afghanistan, where this mineral is famous and highly regarded for producing outstanding rich-blue crystals.

Optical Properties:
• Form: Granular, disseminated or massive. Rarely as deodecahedra or cube crystals.
• Color: Deep blue.
• Relief: Low.
• Interference colors: Isotropic, sometime anomalously anisotropic.


lazurite2020(1).jpg

Blue lazurite crystals, Sar-e-Sang, Afghanistan. From Wikipedia.




lazurite2020(2).jpg

Blue lazurite crystals, Sar-e-Sang, Afghanistan. From Wikipedia.




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
lapislazuli(1).jpg
Blue lazurite, pyroxene (beige), pyrite (black) and calcite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 2x (Field of view = 7mm)		 lapislazuli(2).jpg
Blue lazurite (isotropic, with some anomalously anisotropic blue zones), pyroxene (high interference colors) and calcite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. XPL image, 2x (Field of view = 7mm)		 lapislazuli(3).jpg
Blue lazurite, pyroxene (beige), pyrite (black) and calcite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 2x (Field of view = 7mm)
lapislazuli(4).jpg
Blue lazurite, pyroxene (beige), pyrite (black) and calcite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 2x (Field of view = 7mm)		 lapislazuli(5).jpg
Blue lazurite (isotropic, with some anomalously anisotropic blue zones), pyroxene (high interference colors) and calcite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. XPL image, 2x (Field of view = 7mm)		 lapislazuli(6).jpg
Blue lazurite, pyroxene (beige), pyrite (black) and calcite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 2x (Field of view = 7mm)
lapislazuli(9).jpg
Blue lazurite, pyroxene (beige), pyrite (black) and calcite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 2x (Field of view = 7mm)		 lapislazuli(10).jpg
Blue lazurite, pyroxene (beige), pyrite (black) and calcite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 2x (Field of view = 7mm)		 lapislazuli(11).jpg
Blue lazurite, pyroxene (beige), pyrite (black) and calcite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 2x (Field of view = 7mm)
lapislazuli(52).jpg
Blue lazurite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 10x (Field of view = 2mm)		 lapislazuli(53).jpg
Blue lazurite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 10x (Field of view = 2mm)		 lapislazuli(58).jpg
Blue lazurite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 10x (Field of view = 2mm)
lapislazuli(59).jpg
Blue lazurite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 10x (Field of view = 2mm)		 lapislazuli(60).jpg
Blue lazurite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 10x (Field of view = 2mm)		 lapislazuli(66).jpg
Blue lazurite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 10x (Field of view = 2mm)
lapislazuli(68).jpg
Blue lazurite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 10x (Field of view = 2mm)		 lapislazuli(69).jpg
Blue lazurite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 10x (Field of view = 2mm)		 lapislazuli(74).jpg
Blue lazurite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 10x (Field of view = 2mm)
lapislazuli(75).jpg
Blue lazurite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 10x (Field of view = 2mm)		 lapislazuli(76).jpg
Blue lazurite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 10x (Field of view = 2mm)		 lapislazuli(80).jpg
Blue lazurite crystals in a Lapis Lazuli from Sar-e-Sang, Afghanistan. PPL image, 10x (Field of view = 2mm)