TOURMALINITE  SILVER  ORE

 

Tourmalinite is an uncommon metamorphic rock dominated by finely crystalline tourmaline.  The photos below are of a black-colored, lineated tourmalinite from the Broken Hill Block of New South Wales, Australia.  The tourmalinite has been broken, folded, and intruded by an irregularly-shaped hydrothermal vein mass of argentiferous galena ((Pb,Ag)S - lead silver sulfide).  The silver content is high enough to make this rock a silver ore.  The rock is waaaay more awesome is person than the photos suggest.  It’s one of my favorite rocks.

 

Locality: subsurface sample from the Umberumberka Mine (~31° 53’ 37” South, ~141° 11’ 26” East), 2-3 km west of the town of Silverton, WNW of Broken Hill, Broken Hill Block, far-western New South Wales, southeastern Australia.

 

Stratigraphy: Umberumberka Lode (“Main Lode”) intruding the Willyama Supergroup, upper Paleoproterozoic.

 

Metamorphic age: high-grade metamorphic events affected rocks of this area at ~1660 m.y. and ~1599-1600 m.y.

 

Age of hydrothermal Ag-galena vein emplacement: possibly at ~510-520 m.y., Early to Middle Cambrian.

 

Tourmalinite (black) with argentiferous galena (silvery-white) & minor chalcopyrite and pyrite (both brassy gold).  Field of view ~7.2 cm across.

 


 

Lineated tourmalinite (black) with argentiferous galena (silvery-white) & minor chalcopyrite and pyrite (both brassy gold).  Field of view ~3.6 cm across.

 


 

Argentiferous galena, (Pb,Ag)S.

 


 

Lineated tourmalinite (black) with argentiferous galena (silvery-white) & minor chalcopyrite and pyrite (both brassy gold).  Field of view ~2.6 cm across.

 


 

Most info. summarized from various items of Broken Hill Block geologic literature.

 


 

Collected & generously donated by Molly Tannian.

 


 

 

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