Cuexcomate, Inactive geyser in Puebla, Mexico.

Cuexcomate is a pale grey and beige sinter cone of an inactive geyser standing on Plaza el Cuexcomate in the La Libertad district of Puebla. The cone rises 13 metres above the plaza, measures 23 metres across at its base and weighs an estimated 400 tons. Its crater is 8 metres wide and 17 metres deep, reaching 4 metres below ground level; a metal spiral staircase descends inside, and sulphurous water lies at the bottom.

Cuexcomate formed before the 1064 eruption of Popocatépetl, when geothermal waters rose through Mesozoic limestone and deposited calcite around the vent. The cone was already described in 1585 as a circular rock six or seven estados high with a deep, foul-smelling pool at the bottom. La Libertad, the settlement around it, was incorporated into Puebla in 1943, and a plaque marking its founding was placed on the cone on November 27, 1970.

The name comes from the Nahuatl cuezcomatl, a large earthen jar for storing grain, which the cone resembles. The same word names the handcrafted granaries typical of Morelos. Local residents act as guides, recounting legends about the geyser's formation and pointing out supposed recognizable shapes in the rock.

The geyser stands at the corner of 2 Poniente and 3 Norte in the La Libertad neighbourhood of Puebla. A metal spiral staircase descends into the excavated crater, whose floor lies about 4 metres below ground level. The rock is porous and uneven, so footing on the stairs deserves care.

The structure consists of 99 percent calcite deposits rather than the silica material typically found in most other geysers worldwide. This makes it chemically and mineralogically different from the vast majority of known geothermal formations of this type.