Deposit thickness refers to the measured or estimated vertical or perpendicular dimension of a mineral deposit between its upper and lower boundaries at any given location. It is a fundamental geometric parameter in the characterization and resource estimation of mineral deposits in bauxite, gold, iron ore, diamond, and other mining operations, and has direct implications for the economics, mining method selection, and production planning of any mineral project. Deposit thickness is measured along drill hole intercepts perpendicular to the plane of the ore body (true thickness) or as vertical thickness, depending on the geometry of the deposit and the orientation of the drilling. In gently dipping or flat-lying deposits such as lateritic bauxite, the true thickness and vertical thickness are approximately equal, while in steeply dipping deposits such as narrow gold veins, the distinction between true and apparent thickness is critically important for accurate resource estimation. Failure to apply appropriate thickness corrections can lead to significant overestimation of resources. Deposit thickness varies spatially across most ore bodies as a result of the original depositional or replacement geometry, post-depositional deformation, and weathering. Iso-thickness maps (isopach maps) are prepared by contouring thickness values at drill hole locations across the deposit footprint to visualize these variations and guide mine planning decisions. In bauxite mining, thickness of the ore profile directly determines the volume of resource per unit area of mining concession. In iron ore deposits, particularly in channel iron deposits or BIF-hosted ore bodies, thickness variations are a primary driver of tonnage uncertainty. In kimberlite diamond deposits, the vertical extent of the pipe with depth is a critical determinant of mine life and economic viability.
