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Formula: Na2Ca14Al2Si22O58(OH)8.6H2O
Phyllosilicate (sheet silicate), reyerite group
Crystal System: Trigonal
Specific gravity: 2.51 to 2.58 measured, 2.59 calculated
Hardness: 3½ to 4½
Colour: Colourless, white
Environments
Volcanic igneous environments
Metamorphic environments
Basaltic cavities
Reynerite is found in cavities in basalt and
tuff, associated with calcite,
chlorite, gyrolite,
analcime, pectolite,
thomsonite and natrolite
(HOM).
Localities
At the type locality, the Reyerite type locality, Niaqornat, Nuussuaq Peninsula, Avannaata, Greenland, reyerite occurs
in amygdules within tuff
(HOM).
At 'S Airde Beinn, Isle of Mull, Argyll and Bute, Scotland, UK, reyerite occurs in amygdules in
basalt, within the contact aureole of a volcanic plug
(HOM).
At Rawlings quarry, McKenny, Brunswick county, Virginia, USA, reyerite occurs in amygdules within a
dolerite dike. The
primary minerals are
plagioclase, augite and
olivine, with small amounts of apatite and
opaques. Textures range from aphanitic
porphyritic at the margins of the dike to intergranular to
doleritic near the centre.
Secondary minerals include
serpentine, localised concentrations of
chlorite, and iddingsite (A mixture of
clay minerals, iron oxides and
ferrihydrites) that has
almost entirely replaced olivine.
Minerals found in the amygdules include reyerite, analcime,
chlorite, calcite,
pectolite, and traces of an unidentified radiating fibrous mineral, probably
natrolite.
At the margin of the dike, nearly spherical amygdules are abundant and average 0.2 mm in diameter, whereas near the centre of
the dike they are less common but larger, reaching approximately 10 mm in diameter. In all cases the amygdules are lined with
chlorite. The small amygdules are either completely filled with
chlorite or have a chlorite rim and a
calcite core. Those in the central portion of the dike commonly have cores of
analcime.
As far as could be determined, reyerite-bearing amygdules are restricted to a zone approximately one foot thick near
the centre of the dike. Within this zone reyerite occurs in two modes, either as a relatively pure core in a
chlorite-rimmed amygdule or as a complex intergrowth with
chlorite.
In the first case the reyerite forms radiating aggregates of pearly white to pale green flakes. The greenish colour is
due to chlorite interleaved parallel to the perfect basal cleavage of the
reyerite.
In the second case the reyerite contains numerous scattered intergrowths of
chlorite.
The close association of reyerite with other alteration minerals suggests that it formed subsequent to the emplacement
of the dike. It is concluded that the reyerite-bearing dike has been subjected to low grade regional metamorphism
(AM 58.517-522).
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