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Formula: Ca4Pb6(Si2O7)3Cl2
Sorosilicate (Si2O7 groups)
Crystal System: Hexagonal
Specific gravity: 5.42 to 5.55 measured, 5.63 calculated
Hardness: 4
Streak: White
Colour: White
Common impurities: Fe,Mn,Zn,H2O
Environments
Metamorphic environments
Hydrothermal environments
Localities
At the Långban mine, Långban Ore District, Filipstad, Värmland County, Sweden, nasonite occurs in
calcite-filled fissures in a metamorphosed iron-manganese deposit with
manganoan diopside, manganoan aegirine,
diopside variety schefferite, lead,
apophyllite, margarosanite
and thaumasite
(Dana, HOM).
At the Torr Works Quarry (Merehead Quarry), Cranmore, Mendip, Somerset, England, UK, a large
goethite specimen has been found
with patches of bright blue nasonite up to 3 mm across on the interface between botryoidal
goethite and the other silicates infilling cavities. On another specimen
nasonite occurs as small (<1 mm) blue grains and patches in massive, opaque veins containing
quartz and baryte
(JRS 13.12).
At the type locality, the Parker shaft, Franklin Mine, Franklin Mining District, Sussex county, New Jersey, USA,
nasonite is found in association with barysilite,
datolite, prehnite,
willemite, axinite,
hancockite, clinohedrite,
biotite variety manganophyllite,
glaucochroite,
garnet and baryte
(AM 36.534-537, Dana, HOM).
These minerals occur as irregular masses and indistinct veinlets cutting the
franklinite-willemite ore and owe
their formation to the local introduction of hydrothermal solutions carrying lead, boron and chlorine - all elements
notably rare in the normal ore
(AM 36.534-537).
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