How Does Tungsten Travel in Ore-Forming Fluids?

August 29th, 2025

We combined atomistic simulation, in‑situ spectroscopy, and thermodynamic modelling to reveal how tungsten (W) actually moves in geological systems. The result is a clearer playbook for when W is mobile, and when it drops out.

Mei, Y., Liu, W., Guan, Q., Brugger, J., Etschmann, B., Siégel, C., Wykes, J., & Ram, R. (2024). Tungsten speciation in hydrothermal fluids. Geochimica et Cosmochimica Acta.

Key Takeaways

  • Don’t chase W–Cl: No stable W–Cl transport species in brines—refines geochemical targeting and avoids false positives.
  • Focus on F-rich systems: W moves efficiently as W–F complexes in acidic to near‑neutral fluids; prioritise F‑bearing intrusions and alteration zones.
  • Redox-sulfur context matters: In reduced, neutral–alkaline settings, W travels as thiotungstates; align sampling with expected alteration/IOCG-style footprints.
  • Practical artefacts delivered: Formation constants for key W–F species, stability-field charts, and process envelopes for exploration, processing, and environmental prediction.

What we delivered

  • Decision enablement: Target ranking criteria for F‑rich systems; process envelopes (pH/T/F) for solubility control; environmental mobility bounds in reduced vs oxidised regimes.
  • Formation constants pack: Key W–F species (WO₃F, WO₃F₂²⁻, HWO₃F₂) ready for GWB/PHREEQC use.
  • Stability-field charts: pH–aF and pH–fO₂ at 300 °C, showing when tungstate, thiotungstate, or W–F dominate.

IMPACT — What You Can Do Now

For exploration

  • Focus on F‑rich systems: W moves efficiently as W–F complexes in acidic → near‑neutral fluids; prioritise F‑bearing intrusions/alteration where speciation windows indicate high mobility.

Stability fields of predominating tungsten species at 300 oC and water vapor-saturated pressure.

  • Prioritise F‑bearing intrusions/alteration where speciation windows indicate high mobility.
  • Avoid chasing W–Cl: Evidence shows no stable W–Cl transport species in brines.
  • Use redox‑sulfur context: in reduced, neutral–alkaline settings W travels as thiotungstates; align sampling with expected alteration/IOCG‑style footprints. 

Tungsten speciation in sulfur-bearing solutions as a function of logfO2 and pH

For processing & geometallurgy

  • Tune reagents: speciation windows indicate when fluoride increases W solubility; use this to set pH/T/F conditions for better extraction or to avoid unintended W carryover.
  • Penalty‑element control: understanding W speciation helps anticipate deportment in circuits co‑processing Mo/REE‑rich feeds.

For environment / closure

  • Predict W mobility: apply the delivered constants and diagrams to forecast W transport in sulfidic (thiotungstate) vs fluoride‑bearing waters under site conditions; supports risk assessments and monitoring plans. 

How We Did It

  • AIMD (ab initio molecular dynamics) to 600 °C / 2 kbar to identify stable W complexes in Cl‑, S‑ and F‑bearing fluids and their key bond signatures.

Snapshot of ab initio molecular dynamics simulation of tungsten in NaCl rich fluids

  • In‑situ XAS (mAESTRO hydrothermal cell) experiment at Australian Synchrotron to verify coordination (O vs S vs F) directly in solution.

In-situ Synchrotron X-ray Absorption Spectroscopy (XAS) using mAESTRO cell, can heat up to 400oC, 500 bar

  • Thermodynamic integration & modelling to deliver formation constants for W–F complexes and build stability fields (e.g., pH–aF at 300 °C) for targeting and process envelopes. 

Tags: #Exploration #Processing #Environment #AIMD #XAS #Thermodynamics

Publication link

https://www.sciencedirect.com/science/article/pii/S0016703724003284