Lithium is concentrated by magmatic fractional crystallisation and partial melting which results in higher concentrations in some pegmatites and muscovite-bearing granites. During rock weathering, highly soluble lithium is taken into solution and transported with water. Locations where water is trapped inland, under arid conditions, concentrate the lithium into residual brines. These concentration mechanisms have formed the two deposit types: pegmatites and continental lithium brines in closed basins, which are the source of most mined lithium. Other sources of viable lithium resources include geothermal brines, jadarite, oilfield brines, and clay minerals such as hectorite. Lithium is also often produced as a by-product from potash operations. This diverse range of resource types requires a range of analytical methods for lithium measurement.
While brines are the production target, geologists may also want to analyse solid salt crusts to evaluate the economic potential of associated brines during exploration.
Depending on the range of total dissolved solids (TDS) in water samples, a range of methods is available. Lithium brines with very high total dissolved solids are most appropriately analysed by method ME-ICP15 which provides Li as part of a 28-element suite. Water samples with TDS <6% can be analysed using ME-MS14™ which delivers a more extensive suite of 46 elements, however, is not suitable for high TDS samples due to the sensitivity of the ICP-MS instrument. Physical parameters and alkalinity measurement for brines may be added via package Li-BrPKG. To analyse salt crusts from brine deposits, Li can be reported as a standalone analyte from aqua regia method Li-ICP41, and where the full element suite is sought, request method ME-ICP41.
|Code||Analytes & Ranges (mg/L)|
|ME-MS14™||Li||0.01-10|| Includes a suite of 46 elements relevant to brine exploration in addition to Li.
Requires 50mL brine.
|Li-BrPKG|| pH, conductivity,
|Physical parameters and alkalinity of lithium brines.
Requires 100mL brine.
Lithium in various sedimentary minerals is readily dissolved in acid digestions. In many cases, aqua regia digestions provide better Li recovery than four-acid due to complex chemical reactions which may precipitate varying amounts of insoluble Li salts in the presence of fluoride. Roasting samples prior to four acid digestion, particularly hectorite samples, may mitigate this effect. ALS recommends testing both methods to determine the best option for your deposit or continuing with the same method used in recent analytical work for consistency in the data set.
Multi-element methods by both four-acid (ME-MS61™) and aqua regia (ME-MS41™) digestions are available for these sample types. When higher concentrations of lithium are expected, methods Li-ICP41 and Li-ICP61 can be used that include lithium specific CRMs. For ore grade concentrations, Li-OG63 from a four-acid digestion is recommended that also includes Li-specific CRMs.
|Code||Analytes & Ranges||Description|
|Li-ICP41||Li||10ppm-1%||Aqua regia and ICP-AES finish. Multi-element package also available. 0.5g sample|
|Li-ICP61||Li||10ppm-1%||Four acid and ICP-AES finish. Multi-element package also available. 0.25g sample|
|Li-OG63||Li||0.005%-10%||Ore grade Li by specialised four-acid digestion and ICP-AES finish.
Best suited to Li-bearing silicate sediments. 0.4g sample
|RST-21||Dry roasting pre-treatment||Roasting samples prior to analysis may increase Li recovery due to excess
water content promoting insoluble salt formation.
These deposits host lithium in silicate minerals along with a wide variety of accessory economic elements, including but not limited to boron, beryllium, tantalum, niobium, tin, tungsten, and caesium. Many pegmatite minerals are very resistive to acid digestions, which will under-report element content if used. Sodium peroxide fusion is the recommended decomposition for these deposits.
Due to the presence of acid resistant minerals in these sample types, fusion methods are recommended. Methods offered range from trace level analysis in the ME-MS89L™ method to MS91-PKG which is applicable for intermediate grade samples to ME-ICP82b for ore grade concentrations.
|Code||Analytes & Ranges (ppm)|
|Code||Analytes & Ranges (%)|
|MS91-PKG||This package combines ME-ICP89 with ICP-MS determination of Nb, Ta, Sn, W, U and Th for an extended pegmatite exploration suite. 0.2g sample|
| Assay grade lithium and/or boron by Na2O2 fusion and 0.001%-10% ICP-AES. Our highest precision method for Li and B 0.02%-50% resource determination in known deposits.
Yes. Please indicate on your sample submittal form that the commodity target is lithium, particularly when selecting multi-element packages. This allows ALS to insert lithium-specific Certified Reference Materials for highest quality results and transparency in lab performance.