Colquechaca (Aullagas), Chayanta Province, Potosí Department, Bolivia

Famous spanish colonial Ag mine, still active, which has been the source of some classic Ag sulphosalt specimens, including pyrargyrite and argyrodite.

(There is no selenium in this deposit; the Se minerals sometimes erroneously ascribed to this locality are really from the Virgen de Surumi mine in Pakajake canyon, about 28km NE of Colquechaca.)

Colquechaca and Aullagas are not really separate mineral localities. The name Aullagas appears on very old labels, but is in reality the now uninhabited "ghost" town a bit over 1km from the current town of Colquechaca. Aullagas was an important town during the colonial era, and many roofless building shells remain, but the miners now live in the neighboring town of Colquechaca, at a bit lower elevation. Both towns worked the same ore veins, so the two names really denote a difference in residential district at different periods of history, not different ore deposits. For example, the Gallofa-Embudo vein passes by the now uninhabited town of Aullagas, and used to be worked from there, but that vein is now worked by means of the long Progreso and San Bartolome adits from the town of Colquechaca: different towns, different town names on labels, but same ore veins, same minerals.