Elbaite

Formula: Na(Al1.5Li1.5)Al6(Si6O18)(BO3)3(OH)3(OH)
Cyclosilicate (ring silicate), tourmaline group, elbaite-liddicoatite series, dravite-elbaite series, and the elbaite-schorl series.
Varieties of elbaite:
Achroite - colourless
Indicolite - blue
Paraíba tourmaline - brilliant blue-green
Rubellite - red or pink
Tsilaisite - manganese-bearing elbaite
Verdelite - green
Watermelon tourmaline - green exterior, pink interior
Specific gravity: 2.9 to 3.1
Hardness: 7½
Streak: White
Colour: Green, red to pink, blue, orange, yellow, colourless
Solubility: Insoluble in virtually all acids except HF (Dana)
Environments:

Plutonic igneous environments
Pegmatites
Metamorphic environments
Hydrothermal environments

Elbaite is generally a late-stage mineral in cavities in granite and granite pegmatites characterised by hydrothermal replacement, also in some metamorphic rocks and high-temperature hydrothermal veins; it is detrital in sediments; it occurs rarely in aplite schist or dolomite; it is sometimes replaced by muscovite, lepidolite or cookeite (Dana, Webmin, HOM). Tourmaline growth in cavities requires hot fluids 250 to 600oC), hot gases and abundant boron, sodium, lithium and aluminium (Lapis 3.66). Tourmaline crystallises with schorl first and elbaite last (Lapis 3.71).
Inclusions in elbaite include fluorapatite, pyrite, quartz, albite, native copper, graphite, muscovite and pyrochlore (Lapis 3.65).
Associated minerals include quartz, albite, lepidolite, microcline, garnet, muscovite, beryl, apatite and spodumene (HOM).

At the Sapo mine, Minas Gerais, Brazil, blue-cap elbaite occurs in pegmatite, mostly as loose crystals, but sometimes on an albite or quartz matrix (Min Rec 40.4.290).

At the Batalha mine, Paraíba, Brazil, elbaite occurs in a granite pegmatite cutting a muscovite-quartzite country rock. The presence of copper and to a lesser extent manganese causes the brilliant blue colour; the high concentration of copper is quite unusual. Some crystals have been partially or completely altered to lepidolite. Associated minerals include quartz, lepidolite, schorl, non-cuprian elbaite and niobium-tantalite oxides. Inclusions of native copper and of tenorite have been found in elbaite here. (Min Rec 33-2.127-137).

At the type locality, Fonte del Prete, Elba Island, Tuscany, Italy, elbaite occurs in pegmatite pockets in aplite veins (AM 91.944-952).

Elbaite from Tanzania has characteristic inclusions of apatite, graphite and pyrite.

At the Chickering mine, Cheshire county, New Hampshire, USA, elbaite occurs in a montebrasite-siderite assemblage that is associated with secondary phosphates including wardite (R&M 90-5.415).

Common impurities: Fe,Mn,Cu,Ti,Ca,F

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