With a mapped surface of over 2,500 square kilometres (970 sq mi) it constitutes the largest group of intrusions exposed in the Sierras Pampeanas.
[1][3] Some specific intruded rock types are: biotite-bearing tonalitic gneisses, amphibolite, marble and quartzite.
[4] The pegmatite of Las Tapias in the southwestern part of the batholith makes up Argentina's "most important" beryllium deposit.
Other pegmatites of the batholith have been mined for quartz, feldspar and beryl plus lesser amounts of columbite and tantalite.
[4] Plagioclases have been affected to a much lesser degree by alteration having have slight compositional changes along the crystal rims or limited transformation into muscovite.
[4] A number of fractures of the batholith show greisen alteration with quartz, sericite, fluorite and tourmaline.
[5] The Achala Batholit contains unusual enclaves of biotite and apatite that form layers in the intrusion.