Further Characterisation of Native Copper Inclusions in […]
Copper-bearing tourmaline, also known as Paraiba tourmaline in the trade, may come in a range of colours from blue to green. Similarly, the colour saturation of such copper-bearing tourmalines may vary largely, from saturated and vibrant – also known as “electric” or “neon” – to very light coloured.
A few months ago, a client submitted to SSEF two tourmalines of attractive and matching shape, size and colour, both supposedly being Paraiba tourmalines (Figure 1). Chemical analyses and absorption spectra (UV-Vis-NIR) quickly revealed that their composition and colour cause was much less matching than their v
Last summer, the SSEF received a series of nine small blue cabochons ranging in weight from 0.4 to 1.5 ct. The client assumed that these stones were Paraiba tourmalines from a very early production of the Sao José da Batahla mine in the state of Paraiba in Brazil, as they were safeguarded for several decades
The mineral chrysoberyl BeAl2O4 is an attractive gemstone that shows a wide variation of colours mostly ranging from yellow to green and brownish green to dark brown. These colours are mainly due to the presence of iron and sometimes vanadium as chromophore elements inside the crystal lattice structure.
Gold-coloured platelet inclusions have been reported in copper- bearing tourmaline from Paraíba State in Brazil since the discovery of this highly sought-after gemstone (Fritsch et al., 1990) in the late 1980s. Until now, this extraordinary type of inclusion in tourmaline was mentioned in the literature only
Paraiba or Not? Cu-bearing Tourmaline with a Distinct F […]
Copper-bearing tourmaline from Nigeria is known in the trade since about two decades (Milisenda 2001, Henricus, 2001; Smith et al., 2001; Zang et al., 2001). The first reported material from Nigeria was rather of aquamarine- to amethyst-like colours, but shortly after it was followed by a limited and sporadic p
Cu-containing Thin Sheet Inclusion in Cu-bearing Tourma […]