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Critical Metals and Lithium
The Critical Metals tab is dedicated to evaluating lithium potential and characterizing mineralizing fluids using boron isotopy. It compares your measurements to 10 Li deposits and 3 Li-clay type deposits in the reference database, covering contexts ranging from Andean salars to pegmatites and lacustrine borosilicatites.
When to Use This Tool?
- You have sampled a brine, a geothermal fluid, or a rock extract and want to evaluate its lithium potential.
- You are working on a pegmatite or a leucogranite and wish to compare its Li isotopic signature to reference deposits (Greenbushes, Cinovec, Manono…).
- You have measured δ11B and want to estimate the formation temperature and pH of the mineralizing fluid.
Required Data
| Field | Unit | Impact |
|---|---|---|
| δ7Li | ‰ L-SVEC | Required for the chart and comparison to Li deposits. Typical ranges: −5 to +35 ‰. |
| [Li] Concentration | mg/L (brine) or ppm (rock) | Required to activate the salar potential score. Without [Li], only qualitative isotopic comparison is displayed. |
| δ11B | ‰ NBS 951 | Optional. Activates the δ11B chart and fluid temperature estimation. |
Chart 1: δ7Li vs. [Li] - Comparison to Reference Deposits
![δ7Li vs [Li] chart - reference deposit points (Atacama, Uyuni, Greenbushes, Jadar…), Atacama correlation line, sample point in blue](https://www.isofind.tech/wp-content/uploads/2026/04/Capture-decran-2026-04-10-151851.png)
Figure 1: δ7Li vs. [Li] Chart. Database deposits are positioned by type (salars, pegmatites, Li-clays, geothermal). The Atacama-type correlation line is plotted as a reference.
Li Deposits in the Reference Database - Exact Values
| Deposit | Country | Type | Central δ7Li (‰) | Central [Li] | Unit |
|---|---|---|---|---|---|
| Salar de Atacama | Chile | BRINE_SALAR | +6.0 | 1,700 | mg/L |
| Salar d'Uyuni | Bolivia | BRINE_SALAR | +7.0 | 400 | mg/L |
| Salar d'Arizaro | Argentina | BRINE_SALAR | +7.5 | 400 | mg/L |
| Salton Sea Geothermal Field | USA | BRINE_GEOTHERM | +4.2 | 220 | mg/L |
| Jadar | Serbia | CLAY_LI | +3.0 | 19,500 | ppm |
| Emili (Bacanora) | Mexico | CLAY_LI | +8.0 | 2,700 | ppm |
| Thacker Pass | USA | CLAY_LI | +6.0 | 2,500 | ppm |
| Greenbushes | Australia | PEGMATITE_LI | +1.0 | 34,000 | ppm |
| Manono-Kitotolo | DRC | PEGMATITE_LI | +2.0 | 28,000 | ppm |
| Cinovec / Zinnwald | Czechia / Germany | PEGMATITE_LI | n.d. | 6,500 | ppm |
Pegmatites have [Li] concentrations in ppm (rock) and salars in mg/L (brine) — these units are not directly comparable on the same axis. The chart uses the entered unit to position the point; ensure you provide the correct unit based on the sample type.
Lithium Potential Score
When [Li] is provided, the module calculates a potential score out of 100, available in the results panel:
| Score | Potential | Indicative Reference (Brines) |
|---|---|---|
| 80 – 100 | High | [Li] > 800 mg/L (cf. Atacama 1,700 mg/L). Consistent salar signature. |
| 50 – 79 | Medium | [Li] 200–800 mg/L (cf. Salton Sea 220 mg/L, Uyuni 400 mg/L). To be qualified by Mg/Li. |
| 20 – 49 | Low | [Li] < 200 mg/L or isotopic signature inconsistent with source. |
| < 20 | Marginal | Not economically relevant without significant prior concentration. |
The potential score is an isotopic indicator — not an economic evaluation. It does not account for the Mg/Li ratio, resource depth, or operating conditions. It must be complemented by multi-element ICP-MS analyses and hydrogeological modeling.
Chart 2: δ11B (Optional)
If δ11B is provided, a second chart positions your sample within boron genetic domains. The database contains 3 boron fractionation factors:
| Pair | Valid T | Δ at 25 °C | Δ at 100 °C | Interpretation |
|---|---|---|---|---|
| Aqueous B3–B4 (pH speciation) | 0–100 °C | −4.64 ‰ | +0.67 ‰ | Low-temperature fluid pH proxy |
| B3–Tourmaline | 25–400 °C | −7.8 ‰ | −1.2 ‰ | Fractionation during hydrothermal tourmaline crystallization |
| B4–Calcite (pH proxy) | 0–50 °C | −2.53 ‰ | −1.7 ‰ | Estimation of oceanic or lacustrine pH (paleo-pH) |
Practical Cases
I only have δ7Li, no [Li]
The δ7Li vs. [Li] chart only displays the position on the X-axis (isotopy). The potential score is not calculated. The module still performs a qualitative comparison with the database deposits based solely on the isotopic dimension.
My δ7Li is very positive (+30 ‰ and above)
Highly positive values characterize significant fractionation by adsorption onto clays (smectites, illites). This signals a primary source depleted in ⁶Li following prolonged water-rock interactions. Typical of evaporated surface waters or diagenetic fluids that have long interacted with clays. Correlation with Jadar (+3.0 ‰ / 19,500 ppm) or Emili/Bacanora (+8.0 ‰ / 2,700 ppm) may remain relevant if [Li] is high.
I am working on a pegmatite, not a brine
Enter the δ7Li measured on the mineral (spodumene, lepidolite) and the Li ppm content of the rock. The engine compares this to the three reference pegmatites (Greenbushes δ7Li = +1.0 ‰ / [Li] = 34,000 ppm; Manono δ7Li = +2.0 ‰ / [Li] = 28,000 ppm; Cinovec [Li] = 6,500 ppm). The salar potential score is not suited for this context, but deposit matches remain relevant.
My brine has a high [Li] but an abnormally positive δ7Li
A very positive δ7Li associated with a high concentration may indicate a mixture between a concentrated brine enriched in ⁷Li by secondary fractionation (interface clays) and a primary source. Compare the point's position to the Atacama correlation line: if you are significantly above this line (δ7Li too positive for the [Li]), it indicates active secondary fractionation.