Then, from the Himalaya mine, just outside the city of La Paz, there was hubnerite, as loose, compound, bladed crystals from 5 to 12 cm, bright shiny black, with red flashes infrequently showing (these crystals have been verified as hubnerite, not ferberite
, and as such are a rarity for Bolivia).
is weakly altered within the topazite, with the formation of dissolution microcavities associated with the sequential crystallization of Ta-rich ferberite
, wolframoixiolite, and columbite-tantalite minerals .
The place in question is an entirely landlocked, mountainous, somewhat mysterious-seeming country which boasts a long mining history and has a secure reputation for turning out world-class specimens of--oh, let's see--metallic species (andorite, pyrarygrite, stannite, franckeite, cylindrite), other primary ores (cassiterite, ferberite
), and glamorous phosphates (phosphophyl-lite, paravauxite, vivianite, ludlamite) such as we have long admired and lusted after.
Relative solubilities of ferberite
and scheelite as a function of T, P, pH, and [M.sub.nacl]," Economic Geology, vol.
I have seen crystals of aquamarine and ferberite
that have literally exploded in display cases when placed under hot lights.
Other aesthetic species have also been recovered, including fluorite, quartz, goethite pseudomorphs after siderite, and other important species such as cassiterite, ferberite
, metanovacekite, uranophane and metazeunerite.
Yet another Bolivian follow-up from last year: at Tucson in 2005, Mike Bergmann dazzled us with a couple of flats full of clusters of sharp, brilliant black, untwinned ferberite
crystals to 7 cm from the Tasna mine, Nor Chichas Province, Potosi Department.
Native bismuth, younger than bismuthinite and ferberite
, was occasionally found in the deeper levels.
Microcline is most commonly associated with quartz, topaz, needle-like schorl and, more rarely, ferberite
. Where phenakite is found, it is virtually always associated with microcline crystals.
Ironically for this Year of China at the Main Show, there was almost nothing new in the way of Chinese minerals to be seen--although, of course, there were sterling specimens by the thousands of cinnabar, stibnite, ferberite
, fluorite, etc.
Fluorite in both purple and green crystals occurs in local abundance, often in association with well-developed, lustrous ferberite
Some of the minerals, including ferberite
, arsenopyrite, stannite and fluorite, are found in quartz veins, while others, including scheelite, chalcopyrite and bismuthinite, are found in the skarn.