Tsilaisite Explained

Category:	Tourmaline
Formula:	NaMn^2+3Al6Si6O18(BO3)3(OH)3OH
Imasymbol:	Tsl^[1]
System:	Trigonal
Mohs:	7 to 7.5
Luster:	Vitreous
Streak:	White

Tsilaisite is a manganese rich variety of elbaite tourmaline.^[2] It is also known as Tsilaizite.^[3] Tsilaisite is related Fluor-tsilaisite.^[4] The gem is named after the location it was first found.

History

It was first reported in the Tsilaisina (also called Tsilaizina) Mine in Vakinankaratra, Madagascar.

The gem was originally described as tsilaisite. But then it was discredited in 2006. In 2011 it was reapproved as tsilaisite.^[5]

Characteristics

Color

In plane polarized light, the gem is pleochroic.^[6] Tsilaisite can be deep pink, red, orangish-yellow, brownish-gold, or greenish-yellow.

Chemistry

Manganese makes up to 3% of the gem's chemistry.

Notes and References

1. Warr. L.N.. 2021. IMA–CNMNC approved mineral symbols. Mineralogical Magazine. 85. 3. 291–320. 10.1180/mgm.2021.43. 2021MinM...85..291W. 235729616. free.
2. Book: Manutchehr-Danai, Mohsen. Dictionary of Gems and Gemology. 2013-03-09. Springer Science & Business Media. 978-3-662-04288-5. 485. en.
3. Web site: 2017-03-27. Tsilaisite . 2021-09-27. National Gem Lab. en-US.
4. 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. 10.1180/minmag.2015.079.1.08. 129149776. 0026-461X.
5. Web site: Tsilaisite. 2021-09-27. www.mindat.org.
6. Book: Issues in Geology and Mineralogy: 2013 Edition. 2013-05-01. ScholarlyEditions. 978-1-4901-0698-4. 677. en.