1. Rock material overlying a mineral deposit or coal seam. Also known as baring; top.

2. Material of any nature, consolidated or unconsolidated, that overlies a deposit of useful materials, ores, or coal, especially those deposits that are mined from the surface by open cuts.

3. Loose soil, sand, or gravel that lies above the bedrock.

To charge in a furnace too much ore and flux in proportion to the amount of fuel.