Formula: Ca4Pb6(Si2O7)3Cl2
Sorosilicate (Si2O7 groups)
Specific gravity: 5.55
Hardness: 4
Streak: White
Colour: White
Common impurities: Fe,Mn,Zn,H2O

Metamorphic environments
Hydrothermal environments


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).

Back to Minerals