The Museo del Tesoro on Calle Plaza 25 de Mayo is a small but spectacular private museum dedicated to the precious metals and gemstones of Bolivia. Three floors of a colonial townhouse trace the geological story of the country's mineral wealth — bolivianite (the local name for ametrine, the dual-coloured purple-and-yellow quartz found only in eastern Bolivia), tin, silver, gold, emeralds — followed by their cultural history in pre-Columbian and colonial times.
The collection ranges from raw mineral specimens to finished pieces of indigenous jewellery and colonial silverwork. A workshop in the basement demonstrates traditional silversmithing, and the small shop sells contemporary pieces made on-site. Less visited than the bigger museums and worth an hour for its concentrated subject. Guided tours in English are available on request.