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

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.