Characterization of Emeralds From a Historical Deposit: Byrud (Eidsvoll), Norway

Abstract

lipo in Yunnan, China; Panjshir, Afghanistan; and Gandao, Pakistan. In this article, we refer to "vanadian emeralds" as those that contain more vanadium than chromium, even when the vanadium content is somewhat low. The mechanisms of beryl coloration by Cr and V are very similar (Burns, 1993;Schwarz and Schmetzer, 2002); in 1988, after many years of controversy, vanadium joined chromium as an accepted coloring agent for emerald (CIBJO, 1988). HISTORICAL BACKGROUNDThe Byrud emerald deposit was probably discovered in the 1860s. During these early years, emerald specimens were obtained by several European natural history museums, including Stockholm in

Boiling as a mechanism for colour zonations observed at the Byrud emerald deposit, Eidsvoll, Norway: fluid inclusion, stable isotope and Ar–Ar studies

“…Previous studies indicate that the three‐phase fluid inclusions may have trapped several sulphide phases, such as pyrrhotite, galena and sphalerite, which are distinctive to the Byrud emerald (Rondeau et al . ). The fluid inclusions in the samples studied occur as planes of inclusions along healed fractures, growth zones or as isolated inclusions.…”

“…Both Byrud and the Emmaville‐Torrington deposits share many other characteristics such as: (i) low concentrations of Na 2 O and MgO; (ii) formed in pegmatite sills which intrude black shale; (iii) associated minerals include quartz, feldspars, micas, fluorite, topaz, cassiterite, wolframite and arsenopyrite; (iv) similar pressures and temperatures of formation; and (v) presence of both vapour‐dominate and halite‐bearing fluid inclusions (Rondeau et al . ; Loughrey et al . ).…”

“…From previous studies, the crystals range up to 6 cm in length and 2 cm wide and form hexagonally shaped crystals with flat basal terminations; minor pyramidal faces have also been observed on the terminations of the Byrud emerald (Nordrum & Raade ; Rondeau et al . ). The emerald colour is variable, from translucent and transparent green, bluish green to colourless, with greyish yellow beryl not uncommon.…”

“…Vanadium-rich emerald, such as those from Byrud are relatively rare compared with the more common chromium-rich variety. There are only a few vanadium-rich emerald deposits including Colombia; Lened in the Northwest Territories, Canada; Salininha in Bahia, Brazil; Dyakou in Yunnan, China; Panjshir in Afghanistan; and Gandao in Pakistan Rondeau et al 2008).…”

Pressure-temperature-fluid constraints for the Emmaville-Torrington emerald deposit, New South Wales, Australia: Fluid inclusion and stable isotope studies

“…However, the geological environment at Emmaville and Torrington is more similar to the Byrud emerald deposit in Norway. These two deposits share many characteristics: (1) contain low concentrations of Na 2 O and MgO, (2) formed in pegmatite sills which intrude alum shale, (3) associated minerals include quartz, feldspars, micas, fluorite, topaz, cassiterite, wolframite, and arsenopyrite, (4) strong colour zonations parallel to the basal plane and (5) presence of both vapour-dominate and halite bearing fluid inclusions [29,30]. The main difference between the two is the Emmaville deposit contains more chromium than vanadium (<0.1 mass% V 2 O 3 ) (Figure 4) and Byrud has minor amounts of CH 4 in the fluid inclusions [30].…”