Images
Formula: KNa2LiMn2+2Ti2Si8O24
Phyllosilicate (sheet silicate), neptunite group,
lithium-, manganese- and
titanium- bearing mineral, forms a series with
neptunite
Crystal System: Monoclinic
Specific gravity: 3.17 to 3.20 measured, 3.26 calculated
Hardness: 5 to 6
Streak: Red-brown
Colour: Red
Solubility: Insoluble in acids
Environments:
Plutonic igneous environments
Pegmatites
Manganoneptunite is found as a late segregation mineral in almost all rock types, including
syenite and syenite
pegmatites
(Webmin. HOM).
Localities
At Saint-Amable, Canada, manganoneptunite occurs in miarolitic cavities in a
nepheline syenite sill
(HOM).
At the type locality, Maly Mannepakhk Mountain, Khibiny Massif, Murmansk Oblast, Russia, manganoneptunite was
found locally in the contact zone of the massif, associated with fibrous
aegirine, natrolite,
analcime, lamprophyllite,
murmanite, lomonosovite,
eudialyte, pectolite,
villiaumite and sodalite
(AM11.289-299, HOM), and also with lorenzenite
(AM 12.96-97 )
At Point of Rocks, Colfax county, New Mexico, USA, manganoneptunite occurs in
syenite and syenite
pegmatite
(Dana).
Back to Minerals