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Formula: [Pb4O2Al(OH)5]2(S2O3)2.H2S2Osub>3)(H2O)5
Thiosulphate (containing the group (S2O3)2-)
Crystal System: Monoclinic
Specific gravity: 4.727 calculated for the empirical formula, and 4.741 calculated for the ideal formula
Hardness: 2
Streak: White
Colour: Colourless
Luminescence: Does not fluoresce under long wave or short wave UV
Solubility: In room-temperature dilute hydrochloric acid, slowly becomes cloudy and then very slowly dissolves
Environments
Dinilawiite is a new mineral, approved in 2023 and to date (January 2025) reported only from the type locality.
Localities
The type locality, the Redmond Mine, Waterville Lake, Haywood County, North Carolina, USA, is a very small and
long-inactive lead - zinc mine. The highly
unusual secondary assemblage
lead - zinc -
copper sulphates, thiosulphates and carbonates found here is particularly
noteworthy for yielding phases with structures containing rare, and in some cases novel, structural units based on short
Pb2+–O bonds.
The name "dinilawiite" is based on the Cherokee word meaning twin, because the mineral is ubiquitously twinned. The ore,
consisting mainly of galena and
sphalerite with lesser
chalcopyrite, occurs in an epithermal vein system consisting of disconnected
sulphide-bearing quartz lenses near the contact between a
granite gneiss and a
mica schist. The new minerals occur
in a localised unusual secondary mineral assemblage.
Dinilawiite occurs in vugs in massive galena -
sphalerite - chalcopyrite -
quartz in close association with
hydroredmondite,
steverustite,
sulfatoredmondite and
susannite.
Dinilawiite crystals occur as flattened tablets with angled striations, up to about 0.4 mm across. The mineral is
colourless but sometimes appears light reddish brown due to inclusions or the transmitted colour of the matrix. The streak
is white and the lustre is vitreous
(CJMP 62.871-879).
Dinilawiite from the Redmond Mine - Image
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