The Portable GEO-Scanner is a handheld version of Slimefun's GEO scanning tools. It scans the chunk you click and shows what virtual GEO resources are available there.
Right-click a block with the Portable GEO-Scanner. The clicked block only chooses the chunk to inspect; the result is for the entire chunk, not just that one block.
GEO resources are invisible chunk-based resources used by machines like the GEO Miner and Oil Pump. Use the Portable GEO-Scanner before setting up extraction equipment so you know whether a chunk is worth using.