Images
Images taken under UV illumination show orange (walstromite) and blue
(celsian) fluorescence.
Formula: BaCa2Si3O9
Cyclosilicate (ring silicate), margarosanite group,
barium-bearing mineral
Crystal System: Triclinic
Specific gravity: 3.67 measured, 3.738 calculated
Hardness: 3½
Streak: White
Colour: Colourless to white
Solubility: Easily soluble in cold dilute acid with the production of a silica gel
Luminescence: Faint pink, white and cream fluorescence under short wave UV; distinct pink, pinkish orange, white or cream
fluorescence under long wave UV (Dana). The luminescence centres are Mn2+, Eu2+ and
trivalent rare-earth elements
(EJM 25.1.71-77).
Common impurities: Ti,Al,Fe,Mn,Mg,Sr,K
Environments
Walstromite occurs in metamorphosed sediments associated with
sanbornite, wollastonite,
celsian, taramellite,
pyrrhotite, pyrite,
fresnoite and many other barium
silicates
(Dana).
Localities
At the Gurim anticline, and at Halamish wadi, both in the Hatrurim Basin, Tamar Regional Council, Southern District,
Israel, walstromite occurs disseminated in a
sanbornite-quartz
gneissic metamorphic rock, especially where the
quartz content is high. In small veins of
rankinite paralava within
gehlenite hornfels.
Associated minerals include sanbornite,
quartz, wollastonite,
celsian, taramellite,
pyrrhotite, pyrite,
witherite, fresnoite,
zadovite, gurimite,
rankinite, gehlenite and
garnet
(HOM).
At the Jakobsberg Mine, Jakobsberg ore field, Nordmark District, Filipstad, Värmland County, Sweden, in a sample of
skarn, lead-rich walstromite
was associated closely with celsian,
phlogopite, andradite,
vesuvianite, diopside and
nasonite
(MM 85.2.224-232).
At the type locality, the Esquire No. 7 claim, Big Creek, Big Creek-Rush Creek Mining District, Fresno county, California,
USA, walstromite occurs as individual grains disseminated in
sanbornite-quartz rock, especially
where the quartz content is high. The layers of walstromite appear to
represent original compositional differences in the pre-metamorphic sedimentary rocks. Walstromite also occurs in
wollastonite-bearing
quartzite that contains little or no
sanbornite. Grains up to 12 mm long are not uncommon, and nearly all of the
grains contain tiny inclusions of celsian or
quartz. The walstromite is associated with
sanbornite, quartz,
wollastonite, celsian,
taramellite, pyrrhotite,
pyrite, witherite,
fresnoite and an unidentified blue
iron-barium silicate mineral
(AM 50.318-319).
Rush Creek, Rush Creek deposit, Big Creek-Rush Creek Mining District, Fresno county, California, USA. the area lies
within a body of metamorphosed sediments completely surrounded by
biotite-quartz
diorite. The largest bodies of
sanbornite-quartz rock occur at or
close to the contacts of the metamorphic and plutonic rocks or entirely within the latter. Some of the smaller bodies of
quartz-sanbornite rock are lenses
entirely within the metamorphic rocks which are mostly quartzite.
In one specimen in which walstromite is present in abundance there are many small crystals of a light green
chlorite, ripidolite, and a small
amount of pellyite
(AM 69.358-373).
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