The Sar-e-Sang Lapis Lazuli Deposit

In the Hindukush Mountains, in the far northeast of Afghanistan, a mining district is located that has occupied mankind for more than about 10,000 years. This district comprises spectacular outcrops of lazurite, a mineral of the sodalite group that is the most important component of Lapis Lazuli. Commonly also pyrite and calcite are present. Lapis Lazuli forms up to 6 meter thick lens-like bodies and layers in calcite- and dolomite-marbles, associated with diopside skarn and forsterite-bearing calciphyre, which is essentially a Ca- and Mg-silicates-bearing marble skarn. The formation of Lapis Lazuli is interpreted to result from metasomatic reactions between granitoids and marble. A major contribution of evaporitic rocks is indicated by sequences of anhydrite and whiteschist (Schreyer and Abraham, 1976). A geological sketch map of a typical occurrence of Lapis Lazuli in such a setting is shown below (modified after Yurgenson and Sukharev, 2010). The major mines are located close to Sar-e-Sang at the east side of the Kokcha river. Stratigraphically the deposits belong to the Sakhi formation of the Archean Sanglich Group. The Sar-e-Sang area is well known for spectacular specimens of lazurite, haüyne, sodalite, phlogopite, richterite, marialite, diopsite, dravite and even afghanite, some of which occur in gem quality.