Neptunite

Neptunite
	Neptunite crystals
General
Category	Phyllosilicate
Formula; (repeating unit)	KNa2Li(Fe2+,Mn2+)2Ti2Si8O24
Strunz classification	9.EH.05
Dana classification	70.04.01.01
Crystal system	Monoclinic
Crystal class	Domatic (m) ; (same H-M symbol)
Space group	Cc
Unit cell	a = 16.427(2), b = 12.478(2) ; c = 9.975(1) Å; β = 115.56(1)°; Z = 4
Identification
Color	Black; deep red-brown in thin fragments
Crystal habit	Prismatic or tabular
Twinning	Interpenetrant on {301}
Cleavage	{110} good
Fracture	Conchoidal
Tenacity	Brittle
Mohs scale hardness	5–6
\|re\|er}}	Vitreous
Streak	Brown to red brown
Diaphaneity	Nearly opaque
Specific gravity	3.19–3.23
Optical properties	Biaxial (+)
Refractive index	nα = 1.69–1.6908,; nβ = 1.6927–1.7,; nγ = 1.7194–1.736
Birefringence	0.0294–0.0452
Pleochroism	x = yellow-orange, y = orange, z = deep red
2V angle	36° to 49°
Other characteristics	Piezoelectric
References

Neptunite is a silicate mineral with the formula K Na₂Li(Fe²⁺, Mn²⁺)₂Ti₂Si₈O₂₄. With increasing manganese it forms a series with mangan-neptunite. Watatsumiite is the variety with vanadium replacing the titanium in the formula.

It was first described in 1893 for an occurrence in the Narssârssuk pegmatite of West Greenland.^[2] It is also found within natrolite veins in glaucophane schist within serpentinite in San Benito County, California, US. It also occurs in Mont Saint-Hilaire, Quebec^[5] and in the Kola Peninsula of Russia .^[1]

The mineral is named for Neptune, Roman god of the sea because of its association with aegirine from Àgir, the Scandinavian sea-god.^[2]

The Gemological Institute of America (GIA) identified an 11.78-carat faceted specimen as neptunite based on Raman spectroscopy.^[6]

References

↑ ^1.0 ^1.1 Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (2005). "Neptunite". Mineral Data Publishing. http://www.handbookofmineralogy.org/pdfs/neptunite.pdf.
↑ ^2.0 ^2.1 ^2.2 Neptunite, MinDat.org, http://www.mindat.org/show.php?id=2883
↑ Webmineral
↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine 85 (3): 291–320. doi:10.1180/mgm.2021.43. Bibcode: 2021MinM...85..291W.
↑ Normand, Charles; Tarassoff, Peter (2006). Mineralogy and geology of the Poudrette quarry, Mont SaintHilaire, Quebec. Mineralogical Association of Canada. https://www.mcgill.ca/redpath/files/redpath/guidebook_4a_final2.pdf. Retrieved 12 March 2022.
↑ Cooper, Amy; Allen, Tara (Summer 2013). "Rare faceted neptunite". Gems & Gemology (Gemological Institute of America) 49 (2). https://www.gia.edu/gems-gemology/summer-2013-labnotes-rrare-faceted-neptunite. Retrieved April 18, 2019.

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Original source: https://en.wikipedia.org/wiki/Neptunite. Read more

[Handbook-1] 1.0 ^1.1 Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (2005). "Neptunite". Mineral Data Publishing. http://www.handbookofmineralogy.org/pdfs/neptunite.pdf.

[Mindat-2] 2.0 ^2.1 ^2.2 Neptunite, MinDat.org, http://www.mindat.org/show.php?id=2883

[Webmin-3] Webmineral

[4] Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine 85 (3): 291–320. doi:10.1180/mgm.2021.43. Bibcode: 2021MinM...85..291W.

[5] Normand, Charles; Tarassoff, Peter (2006). Mineralogy and geology of the Poudrette quarry, Mont SaintHilaire, Quebec. Mineralogical Association of Canada. https://www.mcgill.ca/redpath/files/redpath/guidebook_4a_final2.pdf. Retrieved 12 March 2022.

[6] Cooper, Amy; Allen, Tara (Summer 2013). "Rare faceted neptunite". Gems & Gemology (Gemological Institute of America) 49 (2). https://www.gia.edu/gems-gemology/summer-2013-labnotes-rrare-faceted-neptunite. Retrieved April 18, 2019.

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Neptunite

Topic: Chemistry

References