Nambulite
Nambulite | ||
---|---|---|
2V angle (calculated) 44°, (measured) 30° | | |
Dispersion | r > v weak | |
Other characteristics | the Li analogue of natronambulite | |
References | [2][3][4][5] |
Nambulite is a lithium bearing manganese silicate mineral with the chemical formula (Li,Na)Mn4Si5O14(OH).[2] It is named after the mineralogist, Matsuo Nambu (born 1917) of Tohoko University, Japan, who is known for his research in manganese minerals.[6] The mineral was first discovered in the Funakozawa Mine of northeastern Japan, a metasedimentary manganese ore.[2]
Nambulite is formed from the reaction between a hydrothermal solution and rhodonite, and commonly creates veins in the host rock.[7] Other than a collector's gem, however, it has little economic value.
It belongs to the triclinic-pinacoidal crystal system (or triclinic-normal),[3] meaning that it has three axes of unequal length (a, b, c), all intersecting at oblique angles with each other (none of the angles are equal to 90°). It belongs to the crystal class 1, meaning that any point on the crystal that is rotated 360° and then completely inverted will meet with an equal (but opposite) point on the crystal (see centrosymmetry).[8] Its space group is P 1.
The three axes (a, b, c) have different indices of refraction, na=1.707, nb=1.710, nc=1.730.
In a medium with an index of refraction equaling 1.53, Nambulite has a calculated relief of 1.71–1.73, giving it a moderate to high relief. Relief is a measure of the difference between the index of refraction of the mineral and that of the medium (often Canada balsam or other epoxy with an RI of around 1.53–1.54).[9]
Nambulite is an
References
- S2CID 235729616.
- ^ a b c d Nambulite, Mindat.org
- ^ a b c Nambulite Mineral Data. http://webmineral.com/data/Nambulite.shtml
- ^ Thomas, Arthur. (2008) Gemstones: Properties, Identification and Use. London. New Holland Publishers (UK) Ltd.
- ^ a b Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (2005). "Nambulite" (PDF). Handbook of Mineralogy. Mineral Data Publishing. Retrieved 14 March 2022.
- .
- S2CID 140684834.
- ISBN 978-1-946850-02-7.
- ^ ISBN 978-0471721574.
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