Analytical method: UNKNOWN
| Technique | UNKNOWN |
|---|---|
| Material | WHOLE ROCK |
| Mineral | none |
| Institution | Unknown, Unknown, USA |
| Reference | Nelson, Stephen A; Gonzalez, Caver Erika (1992) Geology and K-Ar dating of the Tuxtla volcanic field, Veracruz, Mexico. Bulletin of Volcanology. 55; 1-2, Pages 85-96. 1992. |