Coesite

Coesite
Coesite
	Crossed-polars image of coesite grain (gray) ~1 mm across in eclogite. Small, colored inclusion is pyroxene. Polycrystalline rim is quartz.
General
Category	Tectosilicate, quartz group
Formula; (repeating unit)	SiO2
IMA symbol	Coe
Strunz classification	4.DA.35
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) ; (same H–M symbol)
Space group	C2/c
Unit cell	a = 7.143; b = 12.383; c = 7.143 [Å]; β = 120.00°; Z = 16
Identification
Formula mass	60.0843 g/mol
Color	Colorless
Crystal habit	Inclusions in UHP metamorphic minerals up to 3 mm in size
Fracture	Conchoidal
Tenacity	Brittle
Mohs scale hardness	7.5-8
Luster	Vitreous
Streak	White
Diaphaneity	Transparent
Density	2.92 (calculated)
Optical properties	Biaxial
Refractive index	nx = 1.594; ny = 1.595; nz = 1.599
Birefringence	+0.006
2V angle	60–70
References

Coesite (/ˈkoʊsaɪt/)^[3] is a form (polymorph) of silicon dioxide (Si O₂) that is formed when very high pressure (2–3 gigapascals), and moderately high temperature (700 °C, 1,300 °F), are applied to quartz. Coesite was first synthesized by Loring Coes, Jr., a chemist at the Norton Company, in 1953.^[4]^[5]

^ Warr, L. N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
^ Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C., eds. (1995). "Coesite" (PDF). Handbook of Mineralogy. Vol. 2 (Silica, Silicates). Chantilly, Virginia: Mineralogical Society of America. ISBN 0962209716. Retrieved December 5, 2011.
^ "coesite". Dictionary.com Unabridged (Online). n.d.
^ Coes, Jr., L. (31 July 1953). "A New Dense Crystalline Silica". Science. 118 (3057): 131–132. Bibcode:1953Sci...118..131C. doi:10.1126/science.118.3057.131. PMID 17835139. The word coesite is pronounced as "Coze-ite", after chemist Loring Coes, Jr.
^ Hazen, Robert M. (22 July 1999). The Diamond Makers. Cambridge University Press. p. 91. ISBN 978-0-521-65474-6. Retrieved 2012-06-06.