gems, spinel, Afghanistan, Tajikistan, balas ruby, Kuh-i-Lal, Pamir, geology

The only noble spinel deposit in the USSR, Kukhilal, is located in the Southwestern Pamirs, on the right bank of the Panj River, between the Darai-Sist and Darai-Kukhilal rivers. The deposit area is confined to the southwestern limb of the Shakhdara synclinorium, which is a lower-order structural element of the large Wakhan anticlinorium (Fig. 1). Kukhilal lies at the base of the Precambrian Wakhan crystalline series (16). The rocks comprising the deposit belong to the metamorphic complex of the Goran Formation and are represented by shadow migmatites and predominantly magnesite marbles. Igneous rocks are of distinctly subordinate importance and form thin bodies—concordant, pre-migmatitic amphibolites and younger cross-cutting pegmatites (Fig. 2).