Fresnillo
Zacatecas, Mexico
Epithermal depositsAg (Pb, Zn, Au)
- Type
- Intermediate-sulfidation epithermal (Mexican Silver Belt)
The largest active silver deposit in the world, worked almost continuously since 1554. In 2022 it produced 13.6 million ounces of silver, 34,000 ounces of gold, 22,000 t of lead and 43,000 t of zinc. The mineralisation, about 30 Ma old (Oligocene), forms veins, mantos and chimneys, with potassic, phyllic, argillic and propylitic alteration. The Jarillas and Valdecañas veins were discovered recently.
δ34S in ‰ (per mil) Values of the same system
Standard : V-CDT
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| −8 / −4.1 ‰ | galena Galena δ34S range over all orebodies. A reduced magmatic source typical of intermediate-sulfidation systems, possibly contaminated by sedimentary sulfur. | Camprubi et Albinson 2007, Geological features of the Fresnillo Ag deposit | ||
| −5 / −2 ‰ | sphalerite Sphalerite is always heavier than coexisting galena (sphalerite-galena Δ of about +2 to +3 ‰), consistent with high-temperature equilibrium but with local variations in pH or fO2. | Camprubi et Albinson 2007, Geological features of the Fresnillo Ag deposit |
δ109Ag in ‰ (per mil) Values of the same system
Standard : NIST SRM 978a
| Value | Range | n | Mineral or matrix | Source |
|---|---|---|---|---|
| −0.4 / 0.4 ‰ | acanthite, native silver and silver-bearing minerals (hypogene) Typical global hypogene range, applied to Fresnillo in the Arribas (2020) compilation, where it is one of the seven world-class deposits represented by more than five samples. The narrow range of -0.4 to +0.4 represents the composition of the primary hydrothermal fluids. | Arribas et al. 2020, The Isotopic Composition of Silver in Ore Minerals, Geochemistry Geo… |
Deposits of the same type
- Zacatecas Mexico
- Guanajuato Mexico
- Pueblo Viejo Dominican Republic
- San José (Oruro) Bolivia
- Aysén, northern group (El Toqui, Katerfeld) Chile
- Aysén, southern group (Fachinal, Mina Silva) Chile
- Aysén, southernmost group (El Faldeo, Lago Chacabuco, Lago Cochrane) Chile
- Cerro Negro (Marianas-San Marcos vein system) Argentina
Cite this page
IsoFind Atlas (2026). Fresnillo, isotope signatures. https://www.isofind.tech/isotopes/en/deposits/fresnillo/ (accessed 2026-10-06).
@misc{isofind2026fresnilloisotopesignatures,
title = {Fresnillo, isotope signatures},
author = {{IsoFind Atlas}},
year = {2026},
url = {https://www.isofind.tech/isotopes/en/deposits/fresnillo/},
note = {Accessed 2026-10-06}
}Updated : 2026-10-06