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Formula: Ba4(Fe3+,Ti)4O2[B2Si8O27]Clx
Cyclosilicate (ring silicate), barium- and
boron- bearing mineral
Crystal System: Orthorhombic
Specific gravity: 3.92 measured
Hardness: 5½
Streak: Brown
Colour: Bronze-purple, reddish brown, brownish violet
Solubility: Insoluble in acids
Common impurities: Mn,Pb,Ca,Na,K,H2O
Environments:
Taramellite is a contact-metamorphic mineral associated with calcite,
magnetite, chalcopyrite,
pyrite, pyroxene,
actinolite and celsian
(Dana).
Localities
At the Gun claim, Wilson Lake, Itsi Mountain, Watson Lake mining district, Yukon, Canada, small rough grains of
titanium-bearing taramellite to 0.3 mm have been found embedded in a granular
aggregate of gillespite crystals
(AM 69.358-373).
At the type locality, Candoglia marble quarries, Piedmont, Italy, taramellite occurs in metamorphic rocks rich in
barium silicates, in contact with granitic rocks and associated with pyrite,
magnetite, diopside,
chalcopyrite, celsian,
calcite and actinolite
(Mindat). The specimen from the Milano museum consists mostly of taramellite
intergrown with amphibole, with minor amounts of
calcite, witherite and
celsian
(AM 69.358-373).
At the Madrelena Mine, Tres Pozos, Baja California, Mexico, at the edge of a large body of
granodiorite, a bed of sanbornite -
quartz rocks occurs, in some places only a few metres from the sharp contact
of metamorphic and plutonic rocks. The rocks immediately adjacent to the sanbornite
bed are impure quartzites, schists and
minor calc-silicates. In some places taramellite is easily recognised
by eye as small tabular crystals embedded in leached sanbornite.
(AM 69.358-373).
At Langban, Sweden, taramellite occurs in a metamorphosed Fe-Mn ore body associated with
quartz,
calcite, hematite,
barylite, baryte,
manganoan pectolite,
K-feldspar, manganoan garnet,
melanotekite, barian hedyphane,
rhodonite and manganoan aegirine
(HOM).
At Big Creek, Rush Creek deposit, Big Creek-Rush Creek Mining District, Fresno County, California, USA, there are isolated occurrences
of sanbornite rock with many other barium silicates in the metasediments. These host rocks are
mostly quartzite with some
calc-silicate rocks. Some rocks are free of
sanbornite and gillespite, and consist
principally of granular celsian in which are enclosed taramellite crystals or clusters
up to a few cm in size. Many of the taramellite crystals enclose grains of other minerals, in some cases enclosing
quartz even though there is very little of this in the
celsian matrix. Diopside variety salite and
actinolite tend to form bands in the celsian
matrix or alongside the coarse taramellite crystals or aggregates. Taramellite has been found throughout most of
the area; it is always a minor, though easily recognised, constituent
(AM 69.358-373).
At Rush Creek, Rush Creek deposit, Big Creek-Rush Creek Mining District, Fresno county, California, USA, the largest bodies of
sanbornite-quartz rock occur at or close to the
contacts of metamorphic and plutonic rocks or entirely within the latter.
Taramellite in the barium silicate rocks may be enclosed in quartz or embedded in
sanbornite
(AM 69.358-373).
At Trumbull Peak, Clearing House, Clearing House District, East Belt, Mariposa county, California, USA, taramellite,
sanbornite, gillespite,
celsian, diopside,
quartz, pyrrhotite and
witherite have been found in three barium silicate lenses composed largely of
sanbornite and gillespite. The metamorphic
rocks around the lenses are mostly quartzite, and contain a little
pyrite and limonite. Taramellite is present
in minor amounts in every specimen examined; in places it may include pyrite
(AM 69.358-373).
At the Victor claim, Picacho Peak, New Idria Mining District, San Benito county, California, USA, barium silicate minerals
including joaquinite, fresnoite and
taramellite occur in veins in bodies of metamorphic rocks within an ultra-mafic mass. Other minerals found here include
albite, apatite,
wollastonite and K-feldspar variety adularia.
Taramellite is by far the rarest of all these minerals, and is unusual in that it occurs as free-standing crystals rather
than being embedded in sanbornite or quartz
(AM 69.358-373).
At the Pacific Cement and Aggregate Company (Kalkar Quarry), Santa Cruz, Santa Cruz county, California, USA, barium-bearing
minerals which have been found include taramellite, celsian,
pabstite and witherite. Taramellite has
not been found in place, but only in piles of rock on the quarry floor. The taramellite appears in crystals up to 3 inches long,
mostly intergrown with tremolite. Specimens containing taramellite invariably
also contain pabstite, and meneghinite and
arsenopyrite are common associates
(AM 69.358-373).
At Chickencoop Canyon, Tulare County, California, at the Baumann Ranch Baryte Prospect taramellite occurs in a body
of metasedimentary rocks, mainly mica schist and
impure quartzite, completely enclosed within
tonalite. The barium minerals occur in a zone in
quartzite which consists principally of
sanbornite and witherite with
quartz. Taramellite was found in each of the five specimens examined.
The principal associated minerals are sanbornite,
celsian, diopside,
quartz, pyrrhotite and
witherite, but vary greatly from one specimen to another. Thin veins of
quartz and krauskopfite were found in two
specimens. Witherite is a major constituent of several of the specimens, but
celsian is inconspicuous or lacking
(AM 69.358-373).
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