The fumarolic activity has resulted in the emplacement of substantial deposits of sulfur, which were already mentioned centuries ago.
[5] Volcanoes in the Central Volcanic Zone include Sabancaya, El Misti and Ubinas in Peru and Tacora, Isluga, Irruputuncu, Ollague, San Pedro, Putana, Alitar, Lascar and Lastarria in Chile, Bolivia and Argentina;[3] there are about 34 volcanoes in the Chilean portion of the Central Volcanic Zone alone.
[13] There are traces of a sector collapse scar and of the resulting debris avalanche on the southeastern flank.
[15] Glacial valleys and moraines have been recognized on the eastern, southeastern and southern slopes of the volcano,[3] and cirques have been found at 5,000 metres (16,000 ft) elevation.
[22] On the western and northwestern flanks, solfataras are present[4] both in the form of fumaroles and of steaming ground, and the Aguas Calientes de Tacora hot springs are located 2 kilometres (1.2 mi) southwest of the volcano.
[32] Overall, fumarolic gases at Tacora undergo substantial interaction with rocks and hydrothermal systems before they reach the surface.
[35] Volcanoes of the Peruvian Central Volcanic Zone generally occur within a narrow belt and are usually associated with normal faults.
[38] Later during the Miocene two separate but partially overlapping volcanic episodes occurred, the first of which was dominated by the emplacement of ignimbrites and the second by the growth composite volcanoes, with vigorous activity during the Pliocene and Pleistocene.
[39] The basement beneath Tacora is formed by the Arica Altiplano, a formation lying at about 4,200 metres (13,800 ft) altitude that consists of various sedimentary and volcanic rocks of Pliocene to Pleistocene age.
Minerals contained in the lava flows are biotite, hornblende, olivine,[3] plagioclase and both orthopyroxene and clinopyroxene;[11] alteration has led to the formation of clays.
The volcanic rocks are subdivided into two units, an andesitic-dacitic one that forms the bulk of the volcano dacitic lava dome.
[47] The sulfur develops chiefly from hydrogen sulfide in steam, which precipitates the mineral in rock cavities.
[52] During the early 20th century, sulfur mining was widespread in northern Chile and of high global importance,[53] a number of highly pure deposits of sulfur can be found in northern Chile from the Peruvian border south to the Puna de Atacama region.
[55] A number of mines were active on Tacora volcano,[50] with much of the mining infrastructure being present on the upper northwestern slopes of the mountain;[56] this infrastructure includes cableways, offices, workers' camps and treatment plants both on the mountain and on its foot.
[59] Transport of sulfur occurred through a dedicated railroad down to Villa Industrial on the Arica-La Paz railway,[60] which served the further transport of the sulfur[50] to Arica, from where it was shipped to all of South America;[61] only after the opening of this railway in 1913 was it possible to use the Tacora deposits to the fullest extent.
[52] It is worth noting that the 1929 border treaty between Peru and Chile had explicitly placed Tacora's sulfur deposits entirely within Chilean territory.
The mining operations also played an important political-cultural role, as they exemplified the imposition of a new, modern culture onto the region.
In local belief, Tacora and Sajama were two mountains in competition for two women (the Nevados de Payachata).