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Formula: Ba(Si3Al2)O10.4H2O
Tectosilicate, zeolite group, barium-bearing
mineral
Crystal System: Orthorhombic
Specific gravity: 2.694 to 2.71 measured
Hardness: 4 to 5
Streak: White
Colour: Colourless to white
Solubility: Gelatinises with acids
Environments
Igneous environments
pegmatites
Carbonatites
Hydrothermal environments
Edingtonite occurs as a late-stage hydrothermal mineral in cavities in
mafic igneous rocks and
nepheline syenites; in
carbonatites and in hydrothermal ore veins. In England it occurs
in dolerite
(HOM, Dana).
Associated minerals include thomsonite,
analcime, natrolite,
harmotome, brewsterite,
prehnite and calcite
(HOM).
Localities
The Ice River Alkaline Complex, Golden Mining Division, British Columbia, Canada, consists of a suite of
ijolites, syenites,
carbonatites and late-stage
pegmatites.
Edingtonite occurs in isolated zeolite- and carbonate-rich pockets in
nepheline syenites. It is a late-stage mineral in these pockets,
which were, themselves, one of the last phases of the complex to form. The major constituents of the pockets are
calcite, natrolite and
edingtonite, with minor ancylite,
catapleiite, aegirine,
pyrite and galena
(CM 22.253-258).
The Mount Mather Creek claim, Golden Mining Division, British Columbia, Canada, is a
sodalite-bearing breccia dyke that
consists of carbonate-rich syenite segregations that occur as veins and pods,
and fine-grained banded sodalite plus carbonate fragments in a carbonate-rich matrix.
The sodalite-carbonate segregations consist dominantly of
sodalite, iron-bearing
dolomite, calcite and
microcline, with an extensive suite of trace minerals including
albite, analcime,
ancylite-(Ce), chabazite-Na,
fluorapatite, baryte,
barytocalcite, cancrinite,
galena, goethite,
gonnardite, harmotome,
edingtonite, natrolite,
nordstrandite, pyrite,
quintinite and sphalerite. Alteration
of the primary silicate–carbonate assemblage has resulted in a
secondary assemblage including
albite, analcime,
cancrinite, gonnardite and
nordstrandite after sodalite,
together with complex intergrowths of ancylite-(Ce),
barytocalcite, edingtonite, and a potentially new
magnesium-bearing edingtonite-like mineral. Remobilisation of barium and
strontium from barytocalcite
resulted in crystallisation of late-stage baryte and
strontium-rich calcite
(MM 86.2.282-306).
At the Brunswick No. 12 mine, Bathurst Mining Camp, Bathurst Parish, Gloucester county, New Brunswick, Canada, the deposit is
a massive sulphide body occurring in sedimentary and volcanic rocks. Edingtonite occurs in open fractures in veins,
where the mineral assemblage is edingtonite, chalcopyrite,
galena, pyrite,
sphalerite, barytocalcite,
calcite, dolomite,
quartz, greenalite and
lizardite, and is apparently derived from ascending hydrothermal fluids reacting
with massive sulphides, argillites and siliceous
tuffs
(CM 22.253-258).
At Yukspor Mt, Khibiny Massif, Murmansk Oblast, Russia, edingtonite occurs with
ferricerite-(LaCa), barylite and
other minerals
(MinRec 35.2.176, 35.4.347).
At the type locality, the Kilpatrick Hills, Scotland, UK, edingtonite was found on Lord Blantyre's Estate, West
Kilpatrick, Dumbartonshire, near Glasgow, Scottland, associated with prehnite,
harmotome, calcite,
analcime and thomsonite
(Mindat).
Loanhead Quarry, Beith, North Ayrshire, Scotland, UK, works highly altered
porphyritic basaltic lavas that
are contemporaries of the andesitic lavas at the type locality for
edingtonite 20 km away. Loose material collected close to the quarry face contained edingtonite associated with
harmotome. The matrix consisted of
thomsonite and pink and white analcime
crystals, with specular and micaceous hematite and botryoidal
prehnite. Partial dissolution of the matrix has left colourless to white irregular
platy aggregates of prehnite.
Subsequently, in a prehnite vein intersected by a
baryte vein, harmotome and
edingtonite occurred in a contact alteration zone. The matrix of this zone was mainly massive
prehnite intergrown with
thomsonite and natrolite accompanied by
baryte and calcite. Dissolution channels of
prehnite and
thomsonite/natrolite contained or were
close to recrystallised natrolite,
prehnite, baryte and
calcite.
The edingtonite forms colourless, transparent, complex wedge-shaped crystals, frequently as intergrown aggregates.
Sometimes edingtonite crystals are perched on, or are penetrated by, small well formed
thomsonite needles, and occasionally they partially enclose
harmotome. It also occurs as random single crystals in or on botryoidal
prehnite. Tiny single crystals and intergrown groups of edingtonite with
inclusions of hematite occur in close association with small rosettes of blood-red
platy hematite, also on botryoidal
prehnite. The edingtonite is closely associated with
harmotome, thomsonite,
natrolite, and very rare diaspore
(JRS 6.27-30).
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