Elbaite

1364🗐

mindat:1:1:1364:8🗐

Approved, 'Grandfathered' (first described prior to 1959)

Proposal 24-A is accepted, and a neotype sample is defined for the mineral elbaite, first described in 1913. The type locality is the Rosina pegmatite, located about 100 m south of the village of San Piero in Campo, Elba island, Italy.
A full description of the neotype was published by Bosi et al. (2025).

9.CK.05🗐

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

61.3.1.10

61.3.1.8

61 : CYCLOSILICATES Six-Membered Rings
3 : Six-Membered Rings with borate groups

17.5.5

17 : Silicates Containing other Anions
5 : Borosilicates

Vitreous, Resinous

Transparent, Translucent

Green, blue-green, blue, red to pink, orange, yellow, colourless

The isomorphous substitution of ions forms the different colors of tourmalines. The cations in the structure (such as Fe, Mn, Cr, etc.) exist in a wide range of isomorphous substitutions, which gives tourmaline a very rich color. There are no or very few transition metal ions in colorless tourmaline.
The red hue of tourmaline is attributed to the d-d transition of octahedral Mn3+, Mn2+, or Mn2+-Mn3+ intervalence charge transfer (IVCT) in its crystal structure. The deep blue color is due to Fe2+, Fe3+, and Mn3+. The “neon” blue color of Paraíba tourmaline is attributed to Cu2+ and Mn3+. The yellow color could be associated with both the Fe2+-Ti4+ and Fe2+-Fe3+ intervalence charge transfers. Regarding the color genesis of green tourmalines, many previous experimental studies have shown that it is due to the isomorphous substitution of transition metal ions, such as Cr, V, and Fe, at the Y or Z position in its structure. It has also been shown that the green color of tourmaline is due to defects in the crystal structure of tourmaline.
The chromogenic components iron and manganese were found in the green elbaites; however, the bivariate correlation analysis indicated that the Mn content had no impact on the color, whereas the Fe content significantly affected both the lightness and the hue of green elbaites. The primary factors influencing the color of tourmaline were the absorption band at 720 nm caused by the Fe2+ d-d transitions and the 300 to 400 nm wide absorption edge extending to the visible range due to the O2−-Fe3+ charge transfer. Infrared spectroscopy indicated that the color of tourmalines was also influenced by their structure. As the degree of Y and Z octahedral distortion in the tourmaline lattice increased, the lightness of the tourmaline decreased and its color deepened.

Based on the Raman frequencies of [OH], short-range crystal occupancy assignments of metal cations were inferred for different samples. The UV-visible spectral analysis demonstrated that the symmetric broad absorption band
centered at 725 nm in the blue samples results from intermetallic charge transfer between Fe2+ and Fe3+, with Fe content directly affecting the depth of the blue hue.

Elbaite enriched in Mn (17,346–20,669 μg/g) and Fe (8396–10,750 μg/g). Heat treatment enhanced transparency and induced strong pleochroism (yellowish green parallel c-axis, brown perpendicular c-axis). UV-Vis spectroscopy identified the brown color origin in the parallel c-axis direction: absorption bands at 730 nm (Fe2+ d–d transition, 5T2g → 5Eg), 540 nm (Fe2+→Fe3+ intervalence charge transfer, IVCT), and 415 nm (Fe2+→Ti4+ IVCT + possible Mn2+ contribution). Post-treatment, the 540 nm band vanished, creating a green transmission window and causing the color shift parallel the c-axis. The spectra perpendicular to the c-axis remained largely unchanged. The disappearance of the 540 nm band, attributed to the reduction of Fe3+ to Fe2+ eliminating the Fe2+–Fe3+ pair interaction required for IVCT, is the primary color change mechanism. The parallel c-axis section of the samples shows brown and yellow-green dichroism after heat treatment. A decrease in the IR intensity at 4170 cm−1 indicates a reduced Fe3+ concentration. The weakening or disappearance of the 4721 cm−1 absorption band of the infrared spectrum and the near-infrared 976 nm absorption band of the ultraviolet–visible spectrum provides diagnostic indicators for identifying heat treatment in similar brown elbaite–fluorelbaite.

White

7½ on Mohs scale

Brittle

Poor/Indistinct
on {1120} and {1011}

Irregular/Uneven, Conchoidal

2.9 - 3.1 g/cm³ (Measured)    3.069 g/cm³ (Calculated)

Uniaxial (-)

n_ω = 1.633 - 1.651 n_ε = 1.615 - 1.63

δ = 0.018 - 0.021
Based on recorded range of RI values above.

High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).

Visible

O- Pink, pale green, pale to deep blue
E- Colourless, yellow, olive-green, purplish

Element	% weight
O	53.722 %
Al	20.458 %
Si	18.253 %
B	3.513 %
Na	2.490 %
Li	1.128 %
H	0.437 %

Calculated from ideal end-member formula.

Al, B, H, Li, Na, O, Si - search for minerals with similar chemistry

Fe,Mn,Cu,Ti,Ca,F

Trigonal

3m - Ditrigonal Pyramidal

R3m🗐

a = 15.86(6) Å, c = 7.11(2) Å

a:c = 1 : 0.448

1,548.84 ų (Calculated from Unit Cell)

3

Prismatic to acicular

Rare on {1011}{4041}

Mt. Apatite, Maine, USA. ICDD 26-964.

Lithium-rich granitic pegmatites, metamorphic rocks and high temperature hydrothermal veins.

ⓘ Rosina vein (Rosina pegmatite), San Piero in Campo, Campo nell'Elba, Livorno Province, Tuscany, Italy

Neotype material is deposited in the collections of the Museo Universitario di Scienze della Terra (MUST), Dipartimento di Scienze della Terra, Sapienza Università di Roma, Italy, catalogue number 33383/406.

blue shortwave-excited luminescence excited by SW UV caused by titanate groups (TiO₆)

Pyroelectric, piezoelectric

No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Gemstone

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