Base metals are derived from a range of deposit types and host rocks. The lithologies hosting mineralisation range from carbonates, clastic sediments, and igneous rocks. The choice of analysis for base metals of interest will depend on sample mineralogy and concentration of the elements of interest. Tin, in particular, is often hosted in cassiterite a mineral that is highly resistant to acid digestion, and barite is also acid resistant, therefore a fusion method is necessary for full recovery.
Exploration samples benefit from detection limits that can characterise background with a high degree of precision. Greenfields exploration will often need super-trace detection level methods that are described in our Generative Exploration section, but for exploration where background values are known to be higher, alternative methods can be used.
ALS offers methods from both four-acid (ME-MS61™) and aqua regia digestions (ME-MS41™) that are analysed via ICP-MS instrumentation for sensitive detection limits, with trace level options measured by ICP-AES (ME-ICP61 and ME-ICP41). Fusion decomposition for base metals is best accomplished via an oxidising flux to ensure full recovery, such as trace level sodium peroxide fusion method ME-MS89L™ or ME-ICP81 for higher grade samples.
Code | Analytes & Ranges (ppm) | |||||||
---|---|---|---|---|---|---|---|---|
ME-MS41™ 0.5g sample |
Ag | 0.01-100 | Cs | 0.05-500 | Mo | 0.05-10,000 | Sr | 0.2-10,000 |
Al | 0.01-25% | Cu | 0.2-10,000 | Na | 0.01%-10% | Ta | 0.01-500 | |
As | 0.1-10,000 | Fe | 0.01%-50% | Nb | 0.05-500 | Te | 0.01-500 | |
Au* | 0.02-25 | Ga | 0.05-10,000 | Ni | 0.2-10,000 | Th | 0.2-10,000 | |
B | 10-10,000 | Ge | 0.05-500 | P | 10-10,000 | Ti | 0.005%-10% | |
Ba | 10-10,000 | Hf | 0.02-500 | Pb | 0.2-10,000 | Tl | 0.02-10,000 | |
Be | 0.05-1,000 | Hg | 0.01-10,000 | Rb | 0.1-10,000 | U | 0.05-10,000 | |
Bi | 0.01-10,000 | In | 0.005-500 | Re | 0.001-50 | V | 1-10,000 | |
Ca | 0.01%-25% | K | 0.01%-10% | S | 0.01%-10% | W | 0.05-10,000 | |
Cd | 0.01-1,000 | La | 0.2-10,000 | Sb | 0.05-10,000 | Y | 0.05-500 | |
Ce | 0.02-500 | Li | 0.1-10,000 | Sc | 0.1-10,000 | Zn | 2-10,000 | |
Co | 0.1-10,000 | Mg | 0.01%-25% | Se | 0.2-1,000 | Zr | 0.5-500 | |
Cr | 1-10,000 | Mn | 5-50,000 | Sn | 0.2-500 |
Code | Analytes & Ranges (ppm) | |||||||
---|---|---|---|---|---|---|---|---|
ME-MS61™ 0.25g sample |
Ag | 0.01-100 | Cu | 0.2-10,000 | Na | 0.01%-10% | Sr | 0.2-10,000 |
Al | 0.01%-50% | Fe | 0.01%-50% | Nb | 0.1-500 | Ta | 0.05-500 | |
As | 0.2-10,000 | Ga | 0.05-10,000 | Ni | 0.2-10,000 | Te | 0.05-500 | |
Ba | 10-10,000 | Ge | 0.05-500 | P | 10-10,000 | Th | 0.01-10,000 | |
Be | 0.05-1,000 | Hf | 0.1-500 | Pb | 0.5-10,000 | Ti | 0.005%-10% | |
Bi | 0.01-10,000 | In | 0.005-500 | Rb | 0.1-10,000 | Tl | 0.02-10,000 | |
Ca | 0.01%-50% | K | 0.01%-10% | Re | 0.002-50 | U | 0.1-10,000 | |
Cd | 0.02-1,000 | La | 0.5-10,000 | S | 0.01%-10% | V | 1-10,000 | |
Ce | 0.01-500 | Li | 0.2-10,000 | Sb | 0.05-10,000 | W | 0.1-10,000 | |
Co | 0.1-10,000 | Mg | 0.01%-50% | Sc | 0.1-10,000 | Y | 0.1-500 | |
Cr | 1-10,000 | Mn | 5-100,000 | Se | 1-1,000 | Zn | 2-10,000 | |
Cs | 0.05-500 | Mo | 0.05-10,000 | Sn | 0.2-500 | Zr | 0.5-500 |
Mineralisation, even at moderate grades, may require methods that are suited for high concentrations of the elements of interest. These methods will often have added oxidising reagents to ensure sulphides are fully decomposed.
Methods for low-grade ore analysis include four-acid (ME-ICP61a) and aqua regia (ME-ICP41a) decompositions measured using ICP-AES spectroscopy. Both methods target the portion of the sample that is digested by the acid combination used. For full decomposition, fusion with sodium peroxide and ICP-AES is recommended (ME-ICP81).
Code | Analytes & Ranges (ppm) | |||||||
---|---|---|---|---|---|---|---|---|
ME-ICP41a 0.4g sample |
Ag | 1-200 | Cr | 5-50,000 | Mo | 5-50,000 | Th | 100-50,000 |
Al | 0.05%-50% | Cu | 5-50,000 | Na | 0.05%-50% | Ti | 0.05%-50% | |
As | 10-100,000 | Fe | 0.05%-50% | Ni | 5-50,000 | Tl | 50-50,000 | |
Ba | 50-50,000 | Ga | 50-50,000 | P | 50-50,000 | U | 50-50,000 | |
Be | 5-500 | Hg | 5-50,000 | Pb | 10-50,000 | V | 5-50,000 | |
Bi | 10-50,000 | K | 0.05%-50% | S | 0.05%-10% | W | 50-50,000 | |
Ca | 0.05%-50% | La | 50-50,000 | Sb | 10-50,000 | Zn | 10-50,000 | |
Cd | 5-2,500 | Mg | 0.05%-50% | Sc | 5-50,000 | |||
Co | 5-50,000 | Mn | 25-50,000 | Sr | 5-50,000 |
Code | Analytes & Ranges (ppm) | |||||||
---|---|---|---|---|---|---|---|---|
ME-ICP61a 0.4g sample |
Ag | 1-200 | Cr | 10-100,000 | Na | 0.05%-30% | Ti | 0.05%-30% |
Al | 0.05%-30% | Cu | 10-100,000 | Ni | 10-100,000 | Tl | 50-50,000 | |
As | 50-100,000 | Fe | 0.05%-50% | P | 50-100,000 | U | 50-50,000 | |
Ba | 50-50,000 | Ga | 50-50,000 | Pb | 20-100,000 | V | 10-100,000 | |
Be | 10-10,000 | K | 0.1%-30% | S | 0.05%-10% | W | 50-50,000 | |
Bi | 20-50,000 | La | 50-50,000 | Sb | 50-50,000 | Zn | 20-100,000 | |
Ca | 0.05%-50% | Mg | 0.05%-50% | Sc | 10-50,000 | |||
Cd | 10-10,000 | Mn | 10-100,000 | Sr | 10-100,000 | |||
Co | 10-50,000 | Mo | 10-50,000 | Th | 50-50,000 |
At ore grade concentrations, higher analytical precision is often sought as opposed to analyses for purely exploration applications. At ALS, ore grade methods have tighter quality control limits built-in to provide confidence in important high grade values. Dependent on your needs, ALS offers a selection of suitable methods.
For high grade base metal ores, particularly massive sulphides, we recommend methods utilising oxidising agents such as sodium peroxide with ICP-AES (method ME-ICP81) which will report up to 30% Pb, 20% Sn and 60% Zn amongst other analytes. Other suitable alternatives include ME-ICPORE that includes a strong oxidising digestion with ICP-AES analysis, or a fusion with XRF analysis via methods ME-XRF15 and ME-XRF15c for concentrates. For single element determinations classical chemistry techniques are available.
Code | Analytes & Ranges (ppm) | |||||||
---|---|---|---|---|---|---|---|---|
ME-ICPORE | Ag | 1-1500ppm | Co | 0.001-20 | Mn | 0.005-50 | S | 0.05-50 |
As | 0.005-30 | Cu | 0.001-40 | Mo | 0.001-10 | Sb | 0.005-100 | |
Bi | 0.005-30 | Fe | 0.01-100 | Ni | 0.001-30 | Tl | 0.005-1 | |
Ca | 0.01-50 | Hg | 8-10000ppm | P | 0.01-20 | Zn | 0.002-100 | |
Cd | 0.001-10 | Mg | 0.01-50 | Pb | 0.005-30 |
Fusion with lithium borate can leave some base metal bearing minerals as an insoluble residue. An oxidising sodium peroxide fusion is recommended to report base metals in a sulphide matrix by fusion.
At early stages of exploration, or in regions where alteration has very low concentrations of pathfinder elements, the lowest detection limits may be needed.
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