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Formula: K2(Li,Na,Ca)6(Be6P6)O24(OH)2.1.3H2O
Hydrated phosphate containing hydroxyl, lithium- and
beryllium- bearing mineral
Crystal System: Hexagonal
Specific gravity: 2.65 measured, 2.52 calculated
Hardness: 3½
Streak: White
Colour: Colourless
Luminexcence: Does not fluoresce under UV
Solubility: Only slightly soluble in 30% hydrochloric acid
Environments
Pegmatites
Hydrothermal environments
Although it was approved in 1983, to date (August 2022) tiptopite has been reported only from the type locality.
Localities
At the type locality, the Tip Top Mine, Fourmile, Custer Mining District, Custer county, South Dakota, USA,
tiptopite was discovered during mining operations in the recovery of beryl
from the outer-intermediate zone. This zone consists of large crystals of
microcline perthite, triphylite,
quartz and muscovite, with minor
amounts of beryl, albite,
fluorapatite, elbaite and
columbite-tantalite.
Tiptopite was abundant at the mine, but subsequent mining activity has removed most, if not all, of the area
where it was found. It occured predominantly along fracture surfaces in
beryl, occasionally in quartz, and rarely
in microcline perthite. Tiptopite occurred in the phosphate
pegmatite as a
secondary mineral as clear, colourless, lustrous, radial
aggregates of elongated hexagonal prisms up to 2.0 mm long. Associated minerals included
roscherite, fransoletite,
montgomeryite and englishite
(CM 23.43-46).
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