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Formula: Ba4Mn2+2Si4O12(OH,H2O)3Cl3
Tectosilicate (framework silicate), zeolite group,
barium- and manganese- bearing mineral
Crystal System: Hexagonal
Specific gravity: 3.52 measured, 3.33 calculated
Hardness: 2½ to 3
Streak: Pale orange
Colour: Brown-yellow, may have an orange tint
Luminescence: No fluorescence observed under UV
Solubility: Completely but slowly soluble in dilute hydrochloric acid
Common impurities: Al,Mg,Ca,K
Environments
Although verplanckite was approved in 1964, to date (August 2022) it has been reported only from the type
localities.
Localities
There are two co-type localities, both at Big Creek, Big Creek-Rush Creek Mining District, Fresno county, California,
USA. Verplanckite was first noted in pieces of rock that had been blasted into Big Creek from the
gillespite locality in the
sanbornite deposits. Verplanckite occurs as radial masses of
brownish orange prismatic crystais up to 3 mm long, and as disseminated grains, locally concentrated in thin layers,
in metamorphic sanbornite-quartz
rock near the contact between meta-sediments and biotite-bearing
quartz diorite.
Verplanckite is exceedingly rare; it has also been found sporadically in a drill core. Associated minerals
include quartz, sanbornite,
celsian, diopside,
taramellite, pyrrhotite,
pyrite, fresnoite,
muirite and traskite.
Muirite and verplanckite are commonly associated together, and
muirite and traskite were found
on the same piece of float as was verplanckite
(AM 50.314-340).
Other minerals found at this locality include bigcreekite,
anandite, bazirite,
benitoite, macdonaldite,
pellyite and
titantaramellite
(CM 39.761-768).
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