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Formula: LiAl4Be4(B11Be)O28
Borate, rhodizite group,
lithium- and beryllium- bearing
mineral, a member of the
londonite-rhodizite series
Crystal System: Isometric
Specific gravity: 3.06 measured, 3.19 or 3.266 calculated
Hardness: 8
Streak: White
Colour: Milky white, creamy white to pale pink, pink
Luminescence: Not fluorescent under short wave or long wave UV
Environments
Touretite is a new mineral, approved in 2024 and to date (December 2025) reported only from
the type locality. It is the first mineral found with essential Li, Be, and B.
Localities
The type locality is the Ambalabe pegmatite, Manapa pegmatite Field, Anosiarivo Manapa, Betafo District, Vakinankaratra,
Madagascar. Madagascar so far hosts the only known localities that produced large gem-quality crystals of
londonite-rhodizite, all specimens
having been recovered from a shallow and narrow but long
pegmatite dike hosted in
dolomitic marble. An extreme
enrichment in boron, characteristic for the region, produced several rare
species, including danburite,
tourmaline group minerals and
rhodizite group minerals. The area is well known for
pegmatites mined for gemstones, such as gem varieties of
tourmaline, morganite,
kunzite, spessartine and
danburite. The Ambalabe
pegmatite was mostly mined for mineral specimens and, in
particular, tourmaline and associated minerals. In the core zone of the
body, touretite was found in many rhombic-dodecahedral crystals formed at a late-stage and deposited on
tourmalines, feldspars, and
heavily corroded spodumene and
danburite. Touretite formed together with a late-stage generation of
sugary-white to very pale blue albite and
milky quartz overgrowing pre-existing large crystals or as a new generation of
small crystals. Locally, a pearly white phyllosilicate occurring as small blades is also found in association with
touretite.
The complete list of mineral species associated with touretite includes
quartz, albite,
microcline,
tourmaline group minerals
(dravite, schorl,
elbaite,
fluor-liddicoatite),
spodumene, lepidolite,
danburite, columbite-(Mn),
fersmite,
pyrochlore supergroup minerals and
bismuthinite.
Touretite forms large crystals up to 1 cm across characterised by the dominant rhombic dodecahedron. The colour
is milky white, creamy white to pale pink, or pink, with a vitreous lustre; interpenetration twins, as well as
polysynthetic twins, were observed
(CJMP 63.6.867-878).
Touretite from the Ambalabe pegmatite - Image
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