Images
Formula: Ca5(AsO4)3(OH)
Anhydrous arsenate containing hydroxyl, apatite group
Specific gravity: 3.68
Hardness: 4½
Streak: White
Colour: Light greyish white
Environments:
Johnbaumite occurs in skarn, commonly associated with
biotite and calcite
(Mindat).
Localities
At the Långban mine, Långban Ore District, Filipstad, Värmland County, Sweden, johnbaumite is associated with
tilasite, andradite,
calcite and caryopilite
(HOM).
The type locality is the Franklin Mine, Franklin, Franklin Mining District, Sussex County, New Jersey, USA. Here johnbaumite
occurs in metamorphic zinc-bearing skarn, associated with
zincite, yeatmanite,
roméite, franklinite,
diopside, copper,
calcite and andradite
(Mindat, HOM). Johnbaumite is the massive matrix host for yeatmanite,
which occurs in apparent chemical equilibrium with johnbaumite. Johnbaumite is also host to
diopside, andradite,
franklinite, copper and
roméite. There are indications that diopside was
the first phase to form; it is rimmed by andradite with inclusions of
roméite in the andradite
(AM 65.1143-1145).
Back to Minerals