Report by Tito Maposa
LITHIUM mining firm Prospect Resources has discovered possible large deposits at its Arcadia Mine of caesium, a much sought after chemical element or metal used mainly in high temperature or high pressure oil and gas drilling.
Prospect is an Australia listed firm involved in exploration and mining of lithium, used to make electric vehicle batteries and in the ceramics industry. The company is developing the Arcadia Lithium project near Harare.
The mining giant has discovered significant caesium concentrations in soil, from a number of satellite bodies to Arcadia, notably the Shabaash.
The identified caesium occurs within pollucite, a high value rare caesium mineral that forms in extremely differentiated Lithium-Caesium-Tantalum pegmatite systems.
The primary use of caesium is in Caesium Formate brine used in high temperature/high pressure oil and gas drilling. Prospect’s ground holdings at Shabaash consist of a block of three mining claims, covering some 50 hectares of open bush land.
“Prospect Resources is pleased to announce the presence of significant caesium concentrations in soil, from a number of satellite bodies to Arcadia, notably the Shabaash,” Sam Hosack, managing director of Prospect Resources said.
The Shabaash site is located 3km west of the planned Arcadia Pit.
Background to the Discovery
The area is located within the east-west trending Arcturus limb of the Archaean age Harare Greenstone Belt. It consists largely of metabasalts of the Arcturus formation.
As part of its satellite exploration and ground sterilisation programme, 14,000 soil samples were collected from the area surrounding the drilled resource in 2017 –2018.
Soil samples were collected every 20m on 100m spaced lines, surveyed north-south, but due to time constraints, assayed only for Lithium, by atomic absorption at Zimlabs, Harare.
A number of lithium anomalies were defined, which were subsequently drilled in 2017 -2018. All of these were subsequently drilled and proved to be mineralised pegmatites, albeit in some case too thin and low grade to be economic.
The anomalyat Bermersyde, in contrast, was successfully drilled and, is now part of the reserve, and is the epicentre of the planned Northeast satellite pit.
In December 2019, a small number (61) of stored pulps were selected for re-assay for caesium.
These were selected from samples which had previously returned Lithium anomalies. These pulps were re-assayed successfully at UIS Analytical Services in Centurion, South Africa.