Auyan-Tepui 2010 A new expedition, in March 2010, completed the topographic survey and started the studies on the speleogenesis and the speleothemes of the Cueva Guacamaya, offering new ideas to the interpretation of the karstic phenomenon in the quartzite rocks. The cave, named Cueva Guacamaya, proved to be one of the most interesting cavities explored in that area, characterized by an abundance and variety of opal speleothemes never documented before on the Auyan Tepui. The prevailing horizontal trend along galleries controlled by an interlayer of iron oxides makes it more similar to the large system explored by Czech and Venezuelan speleologists in the Chimantha Tepui than to the caves of tectonic origin explored previously in the Auyan massif in the nearby Aonda zone.