Rock enthusiasts might be interested in Museo Mineralógico which houses a collection of more than 5200 minerals, precious stones, fossils and crystals from around the world, displayed in musty wooden cabinets amid a series of stairways, exposed bricks and glass. It's on the university campus south of town.
Hop on minibus 102 or 2 or any micro marked ‘Sud’ or ‘Ciudad Universitaria’ from opposite the train station or Plaza 10 de Febrero.