The magnetite lavas are primarily aa lava, but other surface features are also found, including pahoehoe features. Columnar morphologies are found on the magnetite, implying that they cooled quickly. There is only one other place in the world where columnar magnetite has been found - Kiirunavaara, in Sweden. Large tubes coated on the inside by magnetite were formed in the lava by escaping gas. Both before and after the magnetite lavas, layers of magnetite-containing pyroclastics were erupted. A aureole separates the magnetite rocks from the host rocks. The magnetite lava flows are thick, the pyroclastics and respectively.:684-685 The pyroclastic-like deposits are porous and fragile and show traces of stratification. The pyroclastics at Laco Sur contain spherules of magnetite. An age of 2.1±0.1 million years has been found for ore by fission track dating. The lavas contain veins likely generated by hydrothermal activity.