Most human extractions of earth materials, such as clay for pottery or coal for power generation, produce some waste. The raw materials are rarely pure, so unwanted detritus is discarded, usually close to the extraction site. Over the last two centuries, exponential industrial growth has resulted in huge increases in the production of mine spoil waste. The management of this waste has become an increasingly important issue.

New technologies allow the mining of ever lower grades of ore, with mounting waste as a byproduct. Early mining actually wasted ore, since only the richest veins were extracted. However, less waste was generated by this high grade ore. Now operations tend to remove varying grades of ore en mass, yielding a higher return, but multiplying the waste produced. Where concentrations are high, it has even been profitable to rework older tailings.

Surface mining accounts for most...