Acamarachi itself is a cone-shaped volcano with steep upper flanks and a lava dome on its northern side.

At the same time starting in the Miocene, andesitic to dacitic eruptive activity has formed large stratovolcanoes.

Most of these volcanoes are remote structures that are unlikely to affect significant population, although wind-driven transport of tephra can potentially cause economic and other damage at considerable distance.

On the volcano's northern flank there is a large lava dome[2] while the rest of the edifice is symmetrical.

Augite, hypersthene and plagioclase are also present, with smaller contents of olivine and quartz.

[15] A study of lava flows at the summit concluded that Acamarachi's last eruption may have occurred during the Holocene.

[15] The volcano is part of a northwest-bound alignment along with Rili, Colachi and Yalquis-Putas, which may be linked to faults underground.

They are both relatively low over the surrounding terrain which is about 4,800 metres (15,700 ft) high and is formed by raised ignimbrites.

Such lack of glaciation is also observed on other mountains in the neighbourhood such as Aucanquilcha and is probably due to the arid climate.

[19] In the past however the mountain was probably extensively glaciated, with glacier lobes forming at its foot and cirques developing around the summit.

[22] The figurines found at Acamarachi may represent mid-level imperial officials, considering the simple tunics they wore.

[32] Acamarachi's figurines are now exposed in the R. P. Gustavo Le Paige Archaeological Museum of San Pedro de Atacama.