Tsilaisite (Tsilaizite) (variety of Elbaite Tourmaline)
Current inventory:  0 gems
 

  
Tsilaisite is named after the Tsilaisina (Tsilaizina) Mine, Tsilaisina pegmatite, on the northern side of Mt. Tsilaisina, Sahatany Pegmatite Field (Mt. Ibity area), Sahatany Valley, Vakinankaratra Region (Betafo - Antsirabé Region), Antananarivo Province, Madagascar.

Discovery year unknown;   IMA status:  Not Valid (IMA discredited in 2006)

Chemistry

Chemical Formula:

Na(Mn²⁺AlFe²⁺)₃Al₆[(O,OH,F)₄|(OH)₃|(BO₃)₃|Si₆O₁₈]

Sodium Manganese Aluminum Iron Boro-Silicate Hydroxide

Molecular Weight:

(Elbaite) 916.68 gm

Composition:

(Elbaite)

Sodium

2.51 %

Na

3.38 %

Na₂O

Lithium

1.89 %

Li

4.07 %

Li₂O

Aluminum

19.13 %

Al

36.15 %

Al₂O₃

Silicon

18.38 %

Si

39.33 %

SiO₂

Boron

3.54 %

B

11.39 %

B₂O₃

Hydrogen

0.44 %

H

3.93 %

H₂O

Oxygen

54.11 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/E.19-10

Nickel-Strunz 10th Ed. ID:

9.CK.05

9 : SILICATES (Germanates)
C : Cyclosilicates
K : [Si₆O₁₈]₁₂- 6-membered single rings, with insular complex anions

Related to:

A variety of Elbaite. Tourmaline Group. Elbaite-Liddicoatite Series, Dravite-Elbaite Series, and the Elbaite-Schorl Series.

Varieties:

None

Synonyms:

None

Crystal Data

Crystallography:

Trigonal - Ditrigonal Pyramidal

Crystal Habit:

(Elbaite) Crystals prismatic to acicular, with prominent trigonal prism and pyramid, to 1.6 m, commonly hemimorphic, striated k [0001]. Also radial, fibrous, and massive.

Twinning:

(Elbaite) Rare, on {1011} or {4041}

Physical Properties

Cleavage:

Poor/Indistinct on {1120} and {1011}

Fracture:

Irregular/Uneven to Conchoidal

Tenacity:

Brittle

Moh's Hardness:

7.5

Density:

2.90- 3.10 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Other:

Piezoelectric, pyroelectric

Optical Properties

Color:

Orangish-Yellow to Brownish-Gold

Transparency:

Transparent to Translucent

Luster:

Vitreous

Refractive Index:

1.615 - 1.651  Uniaxial  ( - ); under strain may show slight biaxiality

Birefringence:

0.0180 - 0.0200

Dispersion:

n/a

Pleochroism:

None

Occurances

Geological Setting:

In granites, granite pegmatites, and some metamorphic rocks; in high-temperature hydrothermal veins; detrital in sediments.

Common Associations:

(Elbaite) Quartz, Albite, Lepidolite, Microcline, Garnet, Muscovite, Beryl, Apatite, Spodumene.

Common Impurities:

(Elbaite) Fe, Mn, Cu, Ti, Ca, F

Type Locality:

Tsilaizina (Tsilaisina) pegmatite, Sahatany Valley, Sahatany Pegmatite Field (Mt Ibity area), Vakinankaratra Region, Antananarivo Province, Madagascar

Year Discovered:

Discovery year unknown; IMA discredited in 2006

View mineral photos:

Elbaite Mineral Photos and Locations

More Information

Mindat.org (Tsilaisite)
Mindat.org (Elbaite)
Webmineral.com (Elbaite)

Tsilaisite, also known as Tsilaizite, is an orangish-yellow to brownish-gold, manganese-rich variety of Elbaite Tourmaline. It was originally reported from the Tsilaisina (Tsilaizina) Mine, Tsilaisina pegmatite, on the northern side of Mt. Tsilaisina, Sahatany Pegmatite Field (Mt. Ibity area), Sahatany Valley, Vakinankaratra Region (Betafo - Antsirabé Region), Antananarivo Province, Madagascar.

These special Tourmalines from this mine are particularly rich in Manganese, up to 3% of their chemistry. While this is not enough to qualify them as a separate variety of Tourmaline, they are certainly unique among Tourmaline gems. Tsilaisite gems are very attractive due to their unique color and vary rare from this location.
 

  
Tsilaisite gems for sale:

We have not photographed our Tsilaisite gems. Please check back soon.