Tsilaisite
Tsilaisite is a magnesium rich variety of elbaite tourmaline.[1] It is also known as Tsilaizite.[2] Tsilaisite is related Fluor-tsilaisite.[3] The gem is named after the location it was first found.[4]
| Tsilaisite | |
|---|---|
| General | |
| Category | Tourmaline |
| Formula (repeating unit) | NaMn2+3Al6Si6O18(BO3)3(OH)3OH |
| Crystal system | Trigonal |
| Identification | |
| Mohs scale hardness | 7 to 7.5 |
| Luster | Vitreous |
| Streak | White |
History
It was first reported in the Tsilaisina (also called Tsilaizina) Mine in Vakinankaratra, Madagascar.[2]
The gem was originally described as tsilaisite. But then it was discredited in 2006. In 2011 it was reapproved as tsilaisite.[4]
Characteristics
Color
In plane polarized light, the gem is pleochroic.[5] Tsilaisite can be deep pink, red,[1] orangish-yellow, brownish-gold,[2] or greenish-yellow.[4]
Chemistry
Manganese makes up to 3% of the gem’s chemistry.[2]
References
- Manutchehr-Danai, Mohsen (2013-03-09). Dictionary of Gems and Gemology. Springer Science & Business Media. p. 485. ISBN 978-3-662-04288-5.
- "Tsilaisite". National Gem Lab. 2017-03-27. Retrieved 2021-09-27.
- Bosi, Ferdinando; Andreozzi, Giovanni B.; Agrosi, Giovanna; Scandale, Eugenio (February 2015). "Fluor-tsilaisite, NaMn3Al6(Si6O18)(BO3)3(OH)3F, a new tourmaline from San Piero in Campo (Elba, Italy) and new data on tsilaisitic tourmaline from the holotype specimen locality". Mineralogical Magazine. 79 (1): 89–101. doi:10.1180/minmag.2015.079.1.08. ISSN 0026-461X. S2CID 129149776.
- "Tsilaisite". www.mindat.org. Retrieved 2021-09-27.
- Issues in Geology and Mineralogy: 2013 Edition. ScholarlyEditions. 2013-05-01. p. 677. ISBN 978-1-4901-0698-4.
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