The precious metals of gold, silver and platinum group elements have been valued for centuries because of their chemical and physical properties. All are commonly used in jewellery today, but also have a variety of other uses ranging from the dental industry for gold to catalysts for platinum.
Precious metals in Afghanistan
There are a total of 93 precious metal occurrences recorded to date in the Afghan mineral occurrence database. These are principally gold with or without silver and base metals. Only one silver-rich occurrence has been identified, and to date no platinum-group mineralisation has been uncovered, although prospective geological terranes do exist in certain parts of the country including the ophiolite assemblages of Kabul and Khost. All the findings to date are the result of work conducted in the 1960s and 70s, principally by Russian geologists who identified two main areas as the most prospective. No more detailed work has been completed since this time, so the possibility exists of finding additional precious metal deposits in other areas using new geological models and exploration techniques.
The provinces of Zabul and Ghazni appear to be the most prospective for skarn-type, porphyry-related and possibly epithermal-style gold mineralisation, due to the subduction-related geological environment during the Cretaceous-Tertiary. More than 50 sites have been recorded to date, including the largest resource currently known in Afghanistan. The Zarkashan skarn deposit was identified in the late 1960s and has Russian category C1 and C2 resources of about 250 000 oz, grading up to 16 g/t Au.
The provinces of Badakhshan and Takhar are also prospective for gold mineralisation with a number of deposits identified to date, including the Vekadur Au-Ag deposit. Preliminary exploration in the 1960s delineated mineralisation grading 46.7 g/t Ag and 4.1 g/t Au for category C1 and C2 resources of just over 30 000 oz. Au. The number of other gold showings and favourable geology, including the discovery of Miocene Cu-porphyry style mineralisation, makes the area highly prospective. The area also has potential for placer-style mineralisation. The most explored is the Samti deposit where two gold-bearing horizons (grading up to 40 g/m3) have been discovered. Summary of the deposit geology.
Skarn-type mineralisation has also been identified in the western Badghis province, associated with Miocene granite porphyry emplacement. Polymetallic mineralisation, up to 3.6% Cu and 5 g/t Au, occurs in pods and veinlets as well as shear zones. Very little is known of the geology of southern Afghanistan, but the discovery of porphyry-style mineralisation in neighbouring Iran and Pakistan highlights the potential of the area. Large resources of Fe oxide like the Hajigak deposit (see Ferrous Metals), contain about 5% sulphides, including chalcopyrite, and should therefore be re-evaluated with modern-day iron oxide-copper-gold models in mind.
A brochure on the potential for gold in Afghanistan has been produced by BGS and can be downloaded by clicking here.