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Formula: KMgFe3+Si4O10(OH)2
Phyllosilicate (sheet silicate), celadonite subgroup,
mica group, forms a series with
muscovite
Crystal System: Monoclinic
Specific gravity: 2.95 -to 3.05 measured, 3 calculated
Hardness: 2
Streak: Greenish white
Colour: Blue-green, olive green, apple green
Solubility: Decomposed by hydrochloric acid
Common impurities: Mn,Ca,Na
Environments:
Metamorphic environments
Basaltic cavities
Celadonite occurs as vesicle lining and coatings in altered volcanic rocks of intermediate to basic compositions,
under low grade metamorphism (Webmin, HOM), and as amygdule fillings in
basalt or
granite
andesite
(HOM).
Celadonite formed in vesicular basalt derives its essential
magnesium, iron, and silica from
olivine, and its other constituents from deuteric solutions; it is most abundant
in these cavities, but
it also replaces olivine, and less commonly
enstatite-ferrosilite
or ground mass material
(AM 26.683-708).
Celadonite occurs throughout the zeolite
and prehnite-pumpellyite facies but does not
occur in the
greenschist facies
(AM 49.1031-1083).
Associated minerals include montmorillonite,
clinoptilolite, heulandite,
laumontite, prehnite,
chlorite, chalcedony,
quartz and calcite
(HOM, Dana).
Localities
There are three co-type localities, Planitz, Zwickau, Saxony, Germany, and Malga Canalece-San Valentino, Brentonico, and
Tierno-Besagno, Mori,
both at Mt. Baldo, Trento Province, Trentino-Alto Adige, Italy.
At the Merehead Quarry, Cranmore, Mendip, Somerset, England, UK, a specimen has been found consisting of crystalline
goethite, calcite and bands of
orange-brown iron oxides,
with a single discontinuous band of celadonite
(JRS 13.14).
At the Cripple Creek mining district, Colorado, USA, celadonite has been reported in vesicles and cracks in
volcanic breccia and altered
tephritic-phonolite
(phonolite with felsics comprising 60-90%
feldspathoids and
alkali feldspar/total feldspar 0.9-0.5)
(Minrec 36.2.167).
At Reno, Nevada, USA, celadonite occurs as vesicular fillings in a fine-grained
olivine
basalt. Most of the cavities are completely filled with celadonite,
but a few are hollow or
contain irregular areas of iron-rich saponite, and a few of the smallest
cavities contain only saponite
(AM 26.683-708).
At Sandoval county, New Mexico, USA, celadonite fills irregular or flattened vesicular cavities up to 10 mm in
size. Some of the vesicles
contain only celadonite, but others contain associated calcite and
saponite
(AM 26.683-708).
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