Patagonia Lithium Ltd (ASX:PL3) has dispatched 24 deep clay core samples from wells JAM 24-01 to JAM 26-09 to US laboratory Geosystems Analytics for porosity testing, in a step the company said is required before its mineral resource consultants can complete the mineral resource estimate for its Formentera project in Argentina.

Key Points

  • 24 core samples composed of clays, with some from basement lithology, have been sent to Geosystems Analytics in the USA for porosity testing
  • The maiden mineral resource estimate was 3.8 million tonnes of lithium carbonate equivalent (LCE), with a drainable resource of 551,000 tonnes of LCE
  • XRD studies identified illite and chlorite as the clay minerals present across all seven samples tested, described by the company as non-expansive clays
  • All responses for the Request for Proposal for the Scoping Study expert reports have been received and are under analysis

Core Porosity Testing Process at Geosystems Analytics

According to the filing, each of the 24 core samples will be prepared and sealed in a test apparatus at Geosystems Analytics. Each test cell will be leak tested and then saturated with brine solution, with four litres of in-situ brine shipped from drilling site well 2. After saturation, test cells will be sequentially pressurised to 120 mbar for approximately two days and then 330 mbar for a further three days. Weight measurements will be collected twice daily. Upon completion, samples will be dried at 60°C for three days and then at 105°C for one day, after which specific yield will be estimated.

Discrepancy Between BMR Gamma Values and Core Porosity Samples

The company disclosed that the further core analysis was initiated due to a discrepancy between BMR Gamma values and several core porosity sample values obtained from Inlab in Argentina and DBS&A Labs in the USA, which used different analytical methods. The filing states that if the clays are determined to be drainable, and not categorised as basement sediments due to higher porosities, it is likely the resource estimate will increase towards the maiden resource estimate of 3.8 million tonnes LCE. The mineral resource consultants will be able to complete their estimate once the Geosystems Analytics analysis is finished.

XRD Clay Analysis Results from Formentera Drilling Program

The filing disclosed results from XRD studies conducted on clay samples, identifying illite and chlorite — tentatively assigned to chamosite — as present in all seven samples tested. The company stated these are non-expansive clays. Additional minerals identified included quartz, plagioclase, halite, calcite, hematite, and zeolites. The filing noted that low transmissivity observed in clay-dominated intervals may be explained by very fine pore size and a high proportion of fines in the matrix, together with compaction, rather than clay swelling. Sample depths tested ranged from 229.69 metres to 475.20 metres across wells JAM-25-05, JAM-26-08, and JAM-26-09.