See the
interactive map of where Piedra Blanca is in relation to surroundings in Bolivar Province. In this map, Piedra Blanca is not marked (as it's so small) but is located just south of San Luis de Pambil in the north western corner of the map. This interesting trekking route takes you due south-east through the small rural villages of Guagraurcu, Monoloma, Lanza Urcu and Pambabuela to Salinas de Guaranda.
Click here for the external link to the interactive map.