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Download hereGENERAL DESCRIPTION
Liddicoatite is a rare tourmaline species. It is an aluminoborosilicate which is rich in calcium and lithium. Like all tourmalines, it is at the same time pyrolectric and piezoelectric.
Its crystals are elongated and prismatic, often well terminated: they can measure several centimetres in length. The zonations in the colour, which one finds within the same crystal, arise from the variation of the chemical composition. It is slightly fluorescent with UV light.
Just like elbaite, liddicoatite is a fine stone used in jewellery: the variation of its colour makes each cut stone unique. The principal deposits of liddicoatite are Antsirabé, Tsilaizina and Anjanabonoina in Madagascar, the Barras de Salinas mines in Brazil, the pegmatites of the island of Utö in Sweden or the Adamello massif in Italy.
One can probably quote much others outcrops rich in tourmaline but a chemical analysis is necessary to distinguish liddicoatite from the other tourmaline species.
The types of this species are kept at the National Museum of Natural History of Washington and at the Museum of Natural History of London.
HISTORY : Species dedicated to Richard T. Liddicoat Junior (1918-2002), American gemmologist and former president of the Gemological Institute of America (GIA)
Species first described by Dunn, Appleman and Nelen in 1977
Type-locality: Antsirabé, Antananarivo, Madagascar
CHEMICAL FORMULA : Ca (Li,Al)3 Al6 (BO3)3 Si6O18 (O,OH,F)4
CRYSTAL SYSTEM : Hexagonal
COLOR : Brown, green, pink, blue. Show color zonations
DIAPHANIETY : Transparent to translucent
LUSTER : Vitreous
STREAK : White or nearly colorless
MORPHOLOGIE : Prismatic crystals, curved
HARDNESS : 7,5
CHEMICAL CLASS: 3,05
DENSITY : VIII - Silicates
GROUP : Tourmaline
STRUNZ CLASS BEFORE 2001 : 8/E.19-80
STRUNZ CLASS AFTER 2001 : 9.CK.05
