Welcome in the mines of ZAMBIA

 

MAP

LOCATION

 

The beryl pegmatites are near the border with Malawi, Mozambique and Zimbabwe.

 

HISTORICAL NEWS

 

The deposit is discovered in 1931 by G. J. Baker, but no work was done till after 1962. It was examined by Hickman and by 1973 some emeralds are produced.

 

MINERALIZATION

 

The emeralds are found in biotite-phlogopite schists in which dark brown to black tourmaline also occur. The rocks associated with emerald-mica schists are talc-magnetite schists and quartz-amphibolite -chlorite schists with secondary quartz veining.

COMPOSITION

 

For each mine we calculated the medium value of lattice parameter.For each mine we calculated the medium value of chemical analyses (analysed 20 point ) by EMPA (Cameca CX 827). Mn, Se, F, Rb are under detection limits except in few cases. Li and Be are not determined.Chemical analyses have been normalized at 85%.H2O was deetermined by EA 1108 Carlo Erba ( gas cromatographer).

 

INFRARED

 

Reflectance FTIR (Fourier Transform Infrared Spectra) of gemstones have been acquired using a microscope IRscopeII (Bruker) accumulating 200 scans with a resolution of a cm-1 or better, in the range 7000-600 cm-1. Here are given only the skeletal bands which lie in the interval 1500-600 cm-1. When the samples were suitably cut in direction parallel or normal to the c axis, polarized spectra were also obtained on the pinacoid or on the basis respectively or both. According to the group theory 6A2u + 16 E1u infrared modes are predicted: the E1u modes are observed in the spectrum when the electric field is perpendicular to the c-axis (ordinary ray) and the A2u modes are observed for the extraordinary ray (E|| c). Therefore, non degenerate bands (A2u) are observed on pinacoids and show intensity changes in polarization, while degenerate bands (E1u) are detected on basis spectra and show only a lowering in intensity in polarized light.

 

BIBLIOGRAPHY

 

1. Graziani G., Gubelin E. and Lucchesi S. "Report on the Investigation of an Emerald from the Kitwe District, Zambia" Australian Gemmologist, 15, 1984, p. 227-234 

2. Koivula J. I. "Tourmaline as an Inclusion in Zambian Emeralds" Gems & Gemology, Winter 1982, p. 225-227 

3. Sinkankas J. 1981 "Emeralds and Other Beryls" Pensylvania, Chilton Book Co. p.371-377