Julgoldite

minerals

babingtonite

ilvaite

Formula:
julgoldite-(Fe2+): Ca2Fe2+Fe3+2(Si2O7)(SiO4)(OH)2.H2O
julgoldite-(Fe3+): Ca2Fe3+Fe3+2(Si2O7)(SiO4)O(OH).H2O
julgoldite-(Mg): Ca2MgFe3+2(Si2O7)(SiO4)(OH)2.H2O
Sorosilicates (Si2O7 groups), pumpellyite group, julgoldite-(Fe2+) forms a series with pumpellyite-(Fe2+) and pumpellyite-(Mg)
Specific gravity: 3.6
Hardness: 4½
Streak: Fe3+ Greenish-olive with a bluish tinge
Colour: Black, Greenish black, Green
Common impurities: julgoldite-(Mg): K
Environments:

Metamorphic environments

Julgoldite-(Fe2+) is associated with apophyllite, baryte, hematite, magnetite, ilvaite, calcite, quartz, chlorite, prehnite, epistilbite, stilbite, pectolite, laumontite, babingtonite and titanite (HOM).

Localities

The Långban mine, Långban Ore District, Filipstad, Värmland County, Sweden, is the type locality both for julgoldite-(Fe2+) and for julgoldite-(Fe3+).
Here julgoldite-(Fe2+) occurs filling cavities and embedded in large plates of apophyllite and minor baryite, which constitute a fissure filling in granular hematite-magnetite ore (AM 56.2157-2158).
Julgoldite-(Fe3+) occurs as a fracture filling in hematite-magnetite ore (Webmin).

The type locality for julgoldite-(Mg) is Sugashima, Toba City, Mie Prefecture, Japan.

Back to Minerals