Bismuth‐melt trails trapped in cassiterite–quartz veins

Abstract

Native bismuth in the form of metallic melt has been considered instrumental to the formation of some metallic ore deposits via a mechanism dubbed the "Liquid Bismuth Collector Model." Here, we provide petrographical documentation of trail-forming, μm-sized blebs of native bismuth in cassiterite-quartz veins from the Santa Bárbara greisen Sn deposit in the Rondônia tin province of northern Brazil. These inclusions suggest the trapping of a Bi melt that took place during vein formation, in a mechanism similar to the entrapment of fluid inclusions. How to cite this article: Guimarães FS, Cabral AR, Lehmann B, et al. Bismuth-melt trails trapped in cassiterite-quartz veins.

Au-Bi-Te(-Cu) Mineralization in the Wawa Gold Corridor (Ontario, Canada): Implications for the Role of Bi-Rich Polymetallic Melts in Orogenic Au Systems

“…Some MSZ assemblages contain intergrowths of bismuth and gold (Figure 7c), a texture similar to those produced during Bi-Au melting experiments [6] and observed in natural environments where melting has been invoked as the mechanism for Au-Bi transport [18,25]. Globular blebs of bismuth, maldonite, and gold that are aligned along fractures in vein quartz of the MSZ (Figure 7d) provide compelling evidence for transport in molten form, as their spherical morphologies are consistent with the immiscibility of the polymetallic melts in a coexisting hydrothermal fluid [23,32], the latter being required for precipitation of the carbonates, silicates, chalcopyrite, and pyrite (Py 4 ) that occur with, and in some cases enclose, the Au-Bi-Te assemblages. In light of these textural relationships, both the F-JSZ and MSZ LMCE assemblages are interpreted to have formed from polymetallic melts.…”

“…Given the apparent similarity in the isotopic and chemical nature of the fluids derived from these two reservoirs [3,8,[13][14][15], the usefulness of the geochemical association of Au with various elements as evidence for a specific fluid source has been a subject of interest (see [16] and references therein), and mineral assemblages and compositions that reflect a Au-Bi-Te association are often taken, in part, to be diagnostic of a magmatic-hydrothermal origin for ore metals [17][18][19][20][21][22][23]. Indeed, both the transport of Au in Bi-rich polymetallic melts and its association with Bi and Te have been repeatedly documented in a variety of magmatic-hydrothermal environments, including skarns [24][25][26][27][28], iron oxide copper-gold (IOCG) and iron oxide cobalt-gold-bismuth deposits [29,30], intrusion-related gold systems [31], greisens [32], and porphyry-epithermal systems [28,33,34]. However, despite the obvious relevance of Birich polymetallic melts in orogenic deposits to discerning both the transport mechanism(s) for Au and potentially the source of Au-bearing fluids, only a few studies have investigated such processes in natural orogenic Au systems [7,17,21].…”