Infill drilling is a systematic drilling program conducted within an existing drill pattern or mineral resource outline with the objective of reducing the spacing between drill holes to improve geological understanding, increase confidence in resource estimates, and upgrade mineral resources from lower confidence categories (inferred or indicated) to higher confidence categories (indicated or measured) as defined under resource reporting codes such as JORC, NI 43-101, or SAMREC. In bauxite, gold, iron ore, and diamond mining, infill drilling is a routine but strategically critical activity in the conversion of geological potential into economically mineable reserves. The decision to undertake infill drilling is typically driven by project development requirements, with feasibility-level studies generally requiring measured and indicated resources to underpin ore reserve declarations and investment decisions. Infill drilling programs are carefully designed by geologists and resource estimation specialists to target specific areas of a deposit where resource confidence is insufficient, where geological complexity or high grade variability requires closer sampling, or where mine planning requires greater certainty of ore continuity ahead of extraction. In gold mining, infill drilling may target high-grade shoots or structurally controlled lodes within open pit or underground mines. In iron ore operations, it is used to establish the precise thickness, continuity, and grade distribution of banded iron formation (BIF) units. Bauxite infill drilling focuses on confirming the thickness, quality, and depth of the bauxite horizon, while in diamond mining it assists in better defining the geometry and grade distribution of kimberlite pipes or alluvial channels.
