Cadence Minerals plc announced that DEV Mineração S/A has completed a new Mineral Resource Estimate in compliance with the Australian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves for the Amapá Iron Ore Project Brazil. Prominas Mining Ltd. was commissioned by DEV Mineração S/A to complete a JORC Code (2012) compliant MRE on the 100% owned mineral assets of DEV comprising the Amapá Iron Ore Deposit located in Amapá State, Brazil. DEV holds the mining rights to the Project, and Cadence, via a joint venture company, owns 27% of DEV.
The classification of Mineral Resources was considered appropriate on the basis of geological confidence, drill spacing, sample interval, QAQC and estimation performance. Before this MRE, the most recent MRE on the Amapá Project was completed in 2020 by Cadence. The 2020 MRE was estimated following the Canadian Institute of Mining, Metallurgy and Petroleum "Estimation of Mineral Resources and Mineral Reserves Best Practice Guidelines".
The 2020 MRE was limited to the Friable Hematite, Friable Itabirite and Friable Altered Itabirite material types. While the current MRE included these material types plus Colluvium and Canga material within the resource statement. This inclusion of Colluvium and Canga into the MRE was deemed appropriate as it was used as ore in historic production.
The inclusion of Colluvium and Canga in the MRE represents the majority of the increase in the current MRE. The geologic units thatunderliethe region consist of Archean basement rocks, TTG terrains, discordantly overlaid by Paleoproterozoic greenstone belts, in turn, overlain by Cenozoic lateritic deposits and Quaternary alluvial materials. In the Amapá System area, the iron ore, calc-silicate and carbonatic rocks occur in two regions.
The first is a synform (locally named APW/APS) above the unit of metabasic rocks and quartz mica schist biotite and muscovite-bearing schist, where the mine is located. The second is Dragão, a mineralised body located 3.5km to NE with orientation NW/SE,assumed as a potential resource and not included in this mineral resources estimate. Mineralisation extends approximately 6.5km in strike length, 1.5km in width, and exists in some areas to more than 100m in depth.
Geological processes have weathered this proto-resource, the hard itabirite, actually considered waste, transforming part of the volume into mineral resources. A 3D geological model was built by an implicit modelling method based on interpreted geological domainsusing the drillhole database and study of the old sections provided by DEV, then used to flag the sample data for statistical analysis and to limit the resource estimation. For this study, statistical and geostatistical analysis was carried out on drilling data composited to 4 m downhole for APW/APS only.
This included variography to model spatial continuity relationships in the geological domains. Geostatistical analysis and interpolation were undertaken using MinePlan© proprietary software. The Ordinary Kriging interpolation method was used for the estimation of Fe, Al2O3, SiO2, P, and Mn, using variogram parameters defined from the geostatistical analysis for the APW/APS domains.
Wet Bulk density values for the Amapá deposit were assigned based on data provided by DEV. The density values were assigned to 15 lithologies based on almost 678 density samples for friable and compact material collected from 2006 to 2012.