MAP

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LOCATION

 

 

Emeralds have been found in Panjshir Valley.  Although travel in this area is extremely dangerous, access to Panjshir from Kabul is quite simple:  travel north by field vehicle to Charikar, from here to north to Jable-os-Seraj, then northest along the north side of Panjshir river to Roka, then on to Senya. From Senya, proceed to the village of Buzmal.

 

 

GEOLOGY

 

 

The area is dominated by the Hindu Kush mountains that form the western end of the Himalayas. This area, the juncture along which the Indo-Pakistan and Asian crustal plates collide, is one of the most dynamic geological regions in the world. The Hindu Kush mountains are at the western end of a succession of important gem-producing regions whose formation can be linked to the sequence of events that resulted in the formation of the Himalayas. The emerald mining district is on the southern slopes of the Hindu Kush, south of the Panjshir river.

 

 

 

MINERALIZATION

 

The emeralds occur within small veins that fill fractures in the host rock.  The host rocks are metamorphosed limestones, calcareous slates, phyllites, and micaceous schist of Silurian-Devonian age. The veins consist mainly of quarzt-albite, apparently related to a local igneous intrusive rock described as a quartz-feldspar porphyry. The emeralds are believed to be of hydrothermal origin and resulted from a chemical reaction between solutions travelling along the fractures and the enclosing host rocks.

 

 

LATTICE PARAMETERS
           
          a=b    9.23 (Å)          
          c        9.21 (Å)          
          c/a     0.99 (Å)

 


GEMOLOGY
 

Refractive index    1.578; 1.585

Color    rich dark green

Birifrangence    0.005

Specific gravity    2.71

Optical absorption spectrum (nm)    inert, sharp line: 682, 679, 660, 646, 635, 612, 477, 472 (nm).


 

 LATTICE COMPOSITION 
        
          Lattice Parameters     
          a=b            9.23 (Å)     
          c                9.21 (Å)     
          c/a             0.99 (Å)                    
                          
                              Average           Range                   Variance
        SiO2                65.91                -0.91    0.83             0.26
        Al2O3             15.88                 -3.07    1.82              3.01
        FeO                 0.45                 -0.42    1.09             0.31
        MgO                1.21                  -0.63    1.44             0.54
        Cr2O3              0.32                -0.32    0.83            0.12
        V2O5                0.11                 -0.11    0.15              0.01
        TiO2                 0.00                0.00    0.03            0.00
        Sc2O3               0.06               -0.06    0.24            0.01
        CaO                  0.05               -0.05    0.16            0.00
        Na2O                0.94               -0.40    0.90           0.24
        K2O                  0.02               -0.02    0.05           0.00
        Cs2O                0.02                -0.02    0.07           0.00
                          
        TOT                85.00               
                          
        H2O                  2.74               

                          
 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, AND Rb are under detection limits except in few cases. Li and Be are not determined
 Chemical analyses have been normalized at 85%
 H2O was determined 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.

 

basis prisma

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

REFERENCES

 

BIBLIOGRAPHY

1. Bowersox G. W. "A Status Report on Gemstones from Afghanistan" Gems & Gemology Winter 1985 p. 192-205 2. Sinkankas J. 1981 "Emeralds and Other Beryls" Pensylvania, Chilton Book Co. p. 542-548

 
 
 
 
 
 
 
 

Welcome to the mines of AFGHANISTAN