Taramellite

minerals

actinolite

celsian

melanotekite

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Formula: Ba4(Fe3+,Ti)4O2[B2Si8O27]Clx
Cyclosilicate (ring silicate), taramellite group
Specific gravity: 3.92
Hardness: 5½
Streak: Brown
Colour: Bronze-purple, reddish brown, brownish violet
Solubility: Insoluble in acids
Common impurities: Mn,Pb,Ca,Na,K,H2O
Environments:

Metamorphic 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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