A tinguaite dyke about 1 m wide occurs north-northwest of Iruya, intruding Precambrian schists.
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A near vertical, sheet-like intrusion extends intermittently over 10 km and has an outcrop width of 20-80 m. The rock, formerly described as kimberlite, is now considered an alnoite.
A peralkaline granite pluton covering 7x3 km cuts and hornfelses Ordovician sediments of the Chiquero Formation northeast of Cobres on the Sierra de Los Cobres. The granite consists of microcline, albite, riebeckite, aegirine and accessories, including pyrochlore.