Elbaite (variety of Tourmaline)

Discovered in 1913; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Na(Al,Li)₃Al₆(BO₃)₃(Si₆O₁₈)(OH)₄

Sodium Lithium Aluminum Boro-Silicate Hydroxide

Molecular Weight:

916.68 gm

Elbaite Composition:

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)

Related to:

Tourmaline Group. Elbaite-Liddicoatite Series. Dravite-Elbaite Series. Elbaite-Schorl Series. The OH-analogue of Fluor-elbaite.

Members of Group:

Tourmaline Group: Adachiite, Chromium-dravite, Chromo-alumino-povondraite, Darrellhenryite, Dravite, Elbaite, Feruvite, Fluor-buergerite, Fluor-dravite, Fluor-elbaite, Fluor-feruvite, Fluor-liddicoatite, Fluor-schorl, Fluor-tsilaisite, Fluor-uvite, Foitite, Liddicoatite, Luinaite-(OH), Magnesiofoitite, Olenite, Oxy-chromium-dravite, Oxy-dravite, Oxy-rossmanite, Oxy-schorl, Oxy-vanadium-dravite, Povondraite, Rossmanite, Schorl, Tsilaisite, UM2000-64-SiO:BFeHKMg, Unnamed (Pb-dominant Tourmaline), Uvite, Vanadio-oxy-chromium-dravite, Vanadio-oxy-dravite

Varieties:

Achroite, Brazilian Emerald, Brazilian Sapphire, Chrome Tourmaline, Chromian Elbaite, Cuprian Elbaite, Fluor-Elbaite, Indicolite, Mn-Tourmaline, Mohrenkopfturmalin, Moor's head Tourmaline, Mushroom Tourmaline, Nickeloan Tourmaline, Paraiba Tourmaline, Rubellite, Siberite, Trapiche Tourmaline, Vanadium Tourmaline, Verdelite, Watermelon Tourmaline

Synonyms:

Aphrizite, Aphrysite, Aphryzite, Ash Drawer, Blue Schorl, Ceylonese Peridot, Chameleonite, Elbaite (of Vernadsky), Lithia Tourmaline, Iochroite, Taltalite, Tourmaline Group, Tourmalinite, Turmaline, Xeuxite, Zeuxite

Crystal Data

Crystallography:

Trigonal - Ditrigonal Pyramidal

Crystal Habit:

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

Twinning:

Rare, on {1011} or {4041}

Physical Properties

Cleavage:

Very poor on {1120}, {1011}

Fracture:

Irregular/uneven to conchoidal

Tenacity:

Brittle

Moh's Hardness:

7.0

Density:

2.90 - 3.10 (g/cm³)

Luminescence:

Fluorescent; weak bluish white to blue under shortwave UV

Radioactivity:

Not Radioactive

Other:

Piezoelectric, Pyroelectric

Optical Properties

Color:

Green, blue, red, orange, yellow, colorless, zoning common parallel to trigonal outline; colorless in thin section.

Transparency:

Transparent to Translucent

Luster:

Vitreous to Resinous

Refractive Index:

1.615 - 1.651  Uniaxial ( - ) 

Birefringence:

0.0180 - 0.0200

Dispersion:

n/a

Pleochroism:

Visible; O = pink, pale green, pale to deep blue; E = colorless, yellow, olive-green, purplish.

Occurances

Geological Setting:

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

Common Associations:

Quartz, Albite, Lepidolite, Microcline, Garnet, Muscovite, Beryl, Apatite, Spodumene.

Common Impurities:

Fe, Mn, Cu, Ti, Ca, F

Type Locality:

Fonte del Prete, San Piero in Campo, Campo nell'Elba, Elba Island, Livorno Province, Tuscany, Italy

Year Discovered:

1913

View mineral photos:

Elbaite Mineral Photos and Locations

Unusual Gem Categories

Fluorescent Gems, Piezoelectric Gems, Pyroelectric Gems

More Information

Mindat.org
Webmineral.com

Elbaite, a sodium lithium aluminium boro-silicate mineral, is a member of the Tourmaline Group of minerals that also includes Dravite, Liddicoatite, Povondraite, Rossmanite, Schorl, Tsilaisite and Uvite. Although the name Elbaite is not that well known, it is the most well known and colorful type of Tourmaline. Most gem Tourmalines are actually Elbaite.

Elbaite is possibly the most colorful type of gem available in the gem market with gems of almost every color of the spectrum available. Some gems and crystals also contain two or more colors as with the very popular Watermelon Tourmaline. There are many gems available with combinations of two colors such as pink/colorless, blue/green and red/green. Achroite is a colorless variety of Tourmaline that is usually, but not always, Elbaite. Indicolite is the blue variety of Elbaite. Rubellite is the pink to red variety of Elbaite. Siberite is a rare variety of Elbaite that is colored lilac, lavender, violet or violet-red to purple. Some of the other Elbaite varieties and colors are Verdelite (green), Paraiba (containing copper), orange and yellow.

Elbaite is also allochromatic, meaning trace amounts of impurities can tint the color of crystals. Elbaite can also be strongly pleochroic meaning it may appear to be different colors or hues when viewed from different angles. Microscopic acicular inclusions in some Elbaite crystals show a cat's eye effect in polished cabochons. Elbaite is also piezoelectric and pyroelectric and some specimens and gems may exhibit weak bluish white to blue fluorescence under shortwave UV light.

Elbaite, the variety of Tourmaline, was named in 1913 by Russian mineralogist Vladimir Ivanovich Vernadsky (Vernadskii) (1863-1945) after its discovery locality on the island of Elba, Italy. However, the name Elbaite was first given in 1883 by German mineralogist Carl Ludwig Giesecke (1761-1833) as the name of a black mineral that turned out to be the mineral Ilvaite which was described and named in 1811 by Norwegian naturalist Henrik Steffens (1773-1845). Steffens named Ilvaite after Ilva, the ancient name of the island of Elba, where it was found. The name Ilva is from the name of the ancient tribe of the Ilvate people who inhabited the island as early as 200 BC.

Elbaite distribution: many localities; some for exceptional specimens follow. In Italy, around San Piero in Campo, Elba. In the Yekaterinburg (Sverdlovsk) district, Ural Mountains, Russia. From Korgal and Mawi, Laghman Province, Afghanistan. In Pakistan, from around Gilgit and Stak Nala. At Ampantsikahitra, Anjanabonoina, Antandrokomby, Maharitra on Mt. Bity, and elsewhere on Madagascar. In the Alto Ligonha district, Mozambique. At Karibib and Usakos, Namibia. In the USA, from Mt. Mica, near Paris, Newry, and elsewhere in Oxford County, Maine; at Haddam, Middlesex County, Connecticut; and from the Pala and Mesa Grande districts, San Diego County, California. In Brazil, from a large district around Araçuaí-Itinga-Salinas, and the Itatiaia district, Governador Valadares, Minas Gerais; at São José da Batalha, Paraíba.

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