Afghanite “Beautiful little rough pieces” from Pakistan.

Afghanite (Afghanit or Afghanita) (Na, Ca, K)8(Si, Al)12O24(SO4,Cl, CO3)3 H2O is a mineral of sodium, calcium, potassium, silicon, aluminum, oxygen, sulfur, chlorine, carbon and hydrogen. It is named after Afghanistan. The hardness on the Mohs scale is 5.5 to 6. The elements Sodium and Potassium are interchangeable, but are always in the same mixing ratio to the other components of the mineral. Chemically speaking, therefore, afghanite is a sodium-potassium-calcium-aluminosilicate with chlorine and sulfate ([SO4]2−) ions. It belongs to the tectosilicates. Afghanite is transparent and forms crystals with vitreous luster, it also occurs in the form of rounded crystallite. The color varies between light and dark blue, in thin slices it is colorless; the stripe color is white. Afghanite was first discovered in the Lapis lazuli-Lagerstätte Ladjuar Medam near Sar-e-Sang in Afghanistan. These Ladjuar Medam deposits were known from ancient times. In 1968 this mineral was described by Pierre Bariand, Fabien Cesbron and Roger Giraud. They named the mineral after the country where it was found.