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Formula: Ca(Li2Al)Al6(Si6O18)(BO3)3(OH)3(OH)
Cyclosilicate (ring silicate), borosilicate,
tourmaline group, forms a series with
elbaite.
Liddicoatite was finally approved in 2025 using an OH-dominant neotype. Previous reports of "liddicoatite" are
often F-dominant and therefore fluor-liddicoatite. The newly
approved liddicoatite is pending publication.
Crystal system: Trigonal
Specific gravity: 3.02 measured, 3.05 calculated
Hardness: 7½
Streak: Light brown, white
Colour: Light-brown, pink to red, green, blue, rarely white
Common impurities: Mn,Fe,Ti,Mg,Na,H2O
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