tezontli.

See also tetzontli, which is a foundation (probably originally involving this kind of stone). We are taking Karttunen's lead here, separating tezontli from tetzontli, although in various sources the distinction becomes blurry (e.g. Hubert Howe Bancroft or Alexander von Humboldt).

"Occuring in 1.4 percent of the burials that include artifacts, tezontli is a relatively rare material in burial offerings...."
Martha Lou Sempowski, Mortuary Practices and Skeletal Remains at Teotihuacán (Salt Lake City: University of Utah Press, 1994), 158.

"Tezontli is the local term for very spongy volcanic rock that occurs in a wide variety of sizes that was used from Tlamimilolpa ceramic phase through the Metepec phase for subflooring, for fill, and cut into facing stone for walls."
The Teotihuacan Valley Project Final Report: The Toltec Period of the Valley (Department of Anthropology, Pennsylvania State University, 1987), 708.

"Architects and sculptors used for preference the jade called nephrite, in the Aztec language quetzaliztli, and the petrified red blood of the porous tezontli; the armorers worked with the itztli, obsidian, in making knives, swords and clubs."
Fernando Benítez, In the Footsteps of Cortés (London: Peter Owen, Ltd., 1957), 203.

teçontli = "another kind of black pumice stone"
Sahagún, Bernardino de, Antonio Valeriano, Alonso Vegerano, Martín Jacobita, Pedro de San Buenaventura, Diego de Grado, Bonifacio Maximiliano, Mateo Severino, et al. Historia general de las cosas de Nueva España (Florentine Codex), Ms. Mediceo Palatino 218–20, Biblioteca Medicea Laurenziana, Florence, MiBACT, 1577. Available at Digital Florentine Codex/Códice Florentino Digital, edited by Kim N. Richter, Alicia Maria Houtrouw, Kevin Terraciano, Jeanette Peterson, Diana Magaloni, and Lisa Sousa, bk. 11, fol. 235v. Los Angeles: Getty Research Institute, 2023. https://florentinecodex.getty.edu/en/book/11/folio/235v?spTexts=&nhTexts= . Accessed 1 February 2026.