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By Root 2010 0

digging it up. This problem especially affects surface mines and open-pit mines, where the ore lies near the surface and is reached by scraping away the earth over it. In contrast, no one now extracts oil by digging the surface off of an entire oil formation; instead, oil companies typically disturb only a small surface area sufficient to drill a well to tap down into the oil formation. Similarly, there are some mines at which the ore body does not lie near the surface but deep underground, and at which tunnels and waste piles disturbing only a small surface area are dug down to the ore body.

Further environmental problems caused by hardrock mining involve water pollution by metals themselves, processing chemicals, acid drainage, and sediment. Metals and metal-like elements in the ore itself—especially copper, cadmium, lead, mercury, zinc, arsenic, antimony, and selenium—are toxic and prone to cause trouble by ending up in nearby streams and water tables as a result of mining operations. A notorious example was a wave of cases of bone disease caused by cadmium discharged into Japan’s Jinzu River from a lead and zinc mine. Quite a few of the chemicals used in mining—such as cyanide, mercury, sulfuric acid, and nitrate produced from dynamite—are also toxic. More recently, it has become appreciated that acid draining out of sulfide-containing ores exposed to water and air through mining causes serious water pollution and leaches out metals. Sediment transported out of mines in runoff water may be harmful to aquatic life, for instance by covering up fish spawning beds. In addition to those types of pollution, the mere consumption of water by many mines is high enough to be significant.

The remaining environmental problem concerns where to dump all the dirt and wastes dug up in the course of mining, consisting of four components: the “overburden” (dirt scraped away to get down to the ore); waste rock found to contain too little mineral to be of economic value; tailings, the ground-up residue of ore after its minerals have been extracted; and the residues of heap-leach pads after mineral extraction. The latter two types of residue are generally left in the tailings impoundment or pad respectively, while the overburden and waste rock are left in dumps. Depending on the laws in the particular country where the mine is located, the methods of disposing of tailings (a slurry of water and solids) involve either dumping them into a river or ocean, piling them up on land, or (most often) piling them up behind a dam. Unfortunately, tailings dams fail in a surprisingly high percentage of cases: they are often designed with insufficient strength (to save money), they are often constructed cheaply from wastes themselves instead of from concrete, and they are built over extended periods so that their condition must be monitored constantly and can’t be subjected to a final inspection declaring them completed and safe. On the average around the world each year, there is one big accident involving a tailings dam. The largest such accident in the U.S. was West Virginia’s Buffalo Creek disaster of 1972, which killed 125 people.

Several of these environmental problems are illustrated by the status of the four most valuable mines on New Guinea and neighboring islands, where I do my fieldwork. The copper mine at Panguna on Papua New Guinea’s Bougainville Island was formerly the country’s largest enterprise and biggest earner of foreign exchange, and one of the largest copper mines in the world. It dumped its tailings directly into a tributary of the Jaba River, thereby creating monumental environmental impacts. When the government failed to resolve that situation and associated political and social problems, Bougainville’s inhabitants revolted, triggering a civil war that cost thousands of lives and nearly tore apart the nation of Papua New Guinea. Fifteen years after the war’s outbreak, peace has still not been fully restored on Bougainville. The Panguna mine was of course closed down, has no prospect of reopening, and the owners and lenders