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Formula: (Zn,Al)3(Si,Al)2O5(OH)4
Phyllosilicate (sheet silicate), serpentine subgroup, forms a
solid solution
with berthierite
Crystal System: Monoclinic
Specific gravity: 3.08 to 3.10 measured, 3.49 calculated
Hardness: 3½ to 4
Streak: White, pale green
Colour: Yellowish white to bluish
Solubility: Dissolves completely in nitric acid, 10% hydrochloric acid and 30% solution of NaOH, gelatinises upon
evaporation, fuses easily to a white enamel
(Dana)
Common impurities: Fe,Cu,Mg,Ca,K
Environments
Fraipontite is a low-temperature clay mineral found with
secondary zinc and
copper minerals in oxidised deposits, often associated with
sauconite.
It forms pseudomorphs after
azurite, cuprite and other minerals,
and is an alteration product of smithsonite
(Dana, Webmin).
Localities
There are three co-type Localities:
The Altenberg mine, Kelmis, Liège, Wallonia, Belgium
The Akdzhal deposit, Akdzhal, Zharma, East Kazakhstan, Kazakhstan
The Sterling mine, Sterling Hill, Ogdensburg, Franklin Mining District, Sussex County, New Jersey, USA
Fraipontite occurs there as crusts of fibres 4-10 mm thick on
smithsonite
(Mindat).
At the Altenberg mine, Kelmis, Liège, Wallonia, Belgium, fraipontite is associated with
smithsonite
(HOM).
At Moresnet, Plombières (Blieberg; Bleiberg; Bleyberg), Liège, Wallonia, Belgium, fraipontite is found on
smithsonite
(Dana).
At the Tsumeb mine, Tsumeb, Oshikoto Region, Namibia, fraipontite is associated with
gebhardite, willemite and
cerussite
(HOM).
At Kap-Kutan Cave System, Kugitangtau Ridge, South Tien-Shan Mountains, Lebap, Turkmenistan, fraipontite is found
coating fluorite, associated with
gypsum, jarosite and
quartz
(Dana).
At the Silver Bill Mine, Costello Mine group, Gleeson, Turquoise Mining District, Cochise County, Arizona, USA,
fraipontite is associated with sauconite
(HOM).
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