On the flank of the volcano, apatite, hematite, and magnetite deposits are found at altitudes of . The volcano is mainly known for these flows, but such material is also found in the form of tephra. The deposits lie on top of flat lava flows of andesitic composition, concentrically around Pico Laco. They are named Laco Norte, Laco Sur, San Vicente Alto, and San Vicente Bajo. The deposits consist of dykes, hydrothermal deposits, lava flows, pyroclastics, and subvolcanic structures and were erupted from parasitic vents and fissures. The magnetite is classified as porphyry-like. Apatite is present as an accessory mineral in the lavas and is abundant in the intrusions. Iron-rich zones also formed in tuffs and lavas. Magnetite in the subvolcanic bodies exists in more massive crystals.:684 The iron-containing rocks include lava flows, ash, and lapilli, as well as ore breccias. The El Laco magnetite lava flows are unique in the world and formed during active subduction.