Source Certain is developing it’s Halo Technology™ (Halo) to support customers with geochemical exploration and will form a key part of our geochemical exploration services. Source Certain is in the process of finalising this technology and commercialising it into a service for the exploration sector. 

Halo is a next-generation scientific technology with over 20 years of development and evaluation in our Australian labs.

Scientific Background

Composition of soil particles

Soil particles generally consist of a core of unweathered primary rock material of variable thickness and a layer of weathered and degraded secondary material surrounding this core. Surrounding this is an extremely thin (picometres to nanometres) tertiary coating of deposited salts from evaporated solutions that have originated at depth and have migrated to the surface by capillary action and evapo-transpiration.

Mineral salt leaching

Mineral salts are leached from rocks by circulating subterranean water migrating to the surface. These salts are derived from both mineralised and un-mineralised sequences and will reflect the geochemistry of the rocks they are leached from. Consequently, the evaporated coatings of soil grains at or near the surface will reflect the sub-cropping geochemistry including that of any mineralised sequence of rocks or orebodies that exist below the surface under the superimposed soil cover.

Pathfinder element leached from orebody

If a migrating solution passes through an orebody on its way to the surface, it will leach metals that are uncharacteristic of any normal lithological sequence and will leach enhanced levels of so-called pathfinder elements reflecting that mineralisation. Consequently, on evaporation of the migrating solution, soil particles are coated with these pathfinder elements at enhanced levels. Although composing a relatively small part of the soil particle, if these elements can be preferentially leached they will give a significant anomaly that will be capable of improving the geochemical signature of the buried or blind orebody at the surface. It is this coating that Halo targets.

Sampling

  • Leaching is performed on a dried soil sample using screened particles (<300 μm diameter).
  • Halo targets and extracts elements from primarily the outer deposited coating on the soil particle.

Comparison to chemical leaching and conventional geochemistry

Halo uses state of the art Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to achieve high levels of precision and accuracy and extremely low detection limits. 

ICP-MS is used to determine analyte concentrations down to parts per trillion. This low level of detection means that even very low analyte concentrations can be determined with a high level of precision, giving greater confidence in using a multi-element interpretational approach to identify the possibility of sub-cropping mineralisation.

Many geochemical exploration initiatives will fail (when using traditional geochemical techniques) to identify potential economic mineralisation because they cannot distinguish between background and the suppressed geochemical response over anomalies associated with buried and blind ore bodies.