Moreover, the tight export quotas have caused world prices to soar, even while holding steady in China. 
 
 Photo 
 
 Officials in two departments of China’s General Administration of Customs in Beijing declined to comment on Thursday evening about the status of rare earth exports. The commerce ministry, which handles trade policy, also had no immediate comment. 
 
 Although deposits of rare earths are found in various parts of the world, including the United States, China produces about 95 percent of the global supply of the minerals. That is largely because rare earth mining and processing can be so environmentally risky, creating toxic and even radioactive wastes, that other countries have tended to avoid or abandon production. Only recently have other nations begun scrambling to develop or expand their own mining capabilities. 
 
 The Chinese shipments resumed Thursday morning only hours before Secretary of State Hillary Rodham Clinton raised the embargo issue at a news conference in Honolulu, where she announced plans to visit China on Saturday to pursue the matter with Chinese officials. 
 
 Mrs. Clinton spoke after meeting with Japan’s foreign minister, Seiji Maehara, and said that the suspension of shipments had been a “wake-up call” and that both countries would have to find alternative sources of rare earth materials. 
 
 Because China is on the opposite side of the international dateline from Honolulu, it was already midday on Thursday in China by the time Mrs. Clinton spoke in Honolulu on Wednesday. Later, after the New York Times Web site reported that the embargo had been lifted, an administration official said the United States was still seeking clarification from China. 
 
 In recent weeks, senior Chinese commerce ministry officials have insisted that they had not issued any regulations halting shipments. They have suggested at various times — implausibly, in the view of industry executives — that the halt resulted from a spontaneous and simultaneous decision by the country’s 32 authorized rare earth exporters not to make shipments, whether because of a deterioration in Sino-Japanese relations or a greater thoroughness on the part of customs inspectors. 
 
 Photo 
 
 Under this year’s quota — 30,300 metric tons of authorized shipments — only a few thousand metric tons remain to be exported in 2010. Meanwhile, annual demand outside China for raw rare earths approaches 50,000 tons, according to industry estimates. 
 
 Advertisement Continue reading the main story 
 
 The Chinese government assigns its quotas to the authorized exporters, who often trade those rights like commodities. As recently as 2008, the quota rights themselves had no market value. But lately, with rising demand, the value of the remaining quotas has soared to the point that the right to export a single ton of rare earths from China now sells for about $40,000, including special Chinese taxes . 
 
 That is a sizable, additional cost for buyers of neodymium, a rare earth used to make lightweight, powerful magnets essential to technologies including giant wind turbines , gasoline- electric cars and Apple iPhones. 
 
 Newsletter Sign Up Continue reading the main story Please verify you're not a robot by clicking the box. Invalid email address. Please re-enter. You must select a newsletter to subscribe to. Sign Up You will receive emails containing news content , updates and promotions from The New York Times. You may opt-out at any time. You agree to receive occasional updates and special offers for The New York Times's products and services. Thank you for subscribing. An error has occurred. Please try again later. View all New York Times newsletters. 
 
 Neodymium sells for about $40,000 a metric ton in China, having recovered from a nose-dive during the global economic crisis. But it sells for twice that much outside the country because of the export restrictions, according to data from Metal Pages, a database service in London . 
 
 The cost of quotas has become exorbitant for users of lanthanum, which is vital for the catalytic converters that clean the exhaust of conventional, gasoline-powered cars. It is mostly produced here in Baotou, a smoggy mining and steel city in China’s Inner Mongolia that is the capital of China’s rare earth industry. Lanthanum sells for less than $4,500 a ton in China, but up to 10 times that much outside China because of the export restrictions. 
 
 Such price differences have created a big incentive for companies to move factories to China, and many already have. 
 
 Photo 
 
 China’s shipping embargo has caused much more distress in Japan than in the United States or Europe, and not just because Japan’s shipments were cut off much earlier. It is because Japan tends to be affected more than other industrial nations by the way China sets its rare earth export quotas. 
 
 China’s quotas — and the shipping embargo — have involved only shipments in which the material has a rare earth content of about 50 percent or more. High-technology materials made from rare earths, like special magnetic powders for the clean energy and electronics industries, or polishing powders for the glass industry, are not subject to quotas and are inexpensively available. 
 
 Because the United States and Europe mainly buy highly processed rare earth powders from China, the customs policy of blocking shipments of raw rare earths had a limited, mostly symbolic effect. Japan, in contrast, is the biggest importer of raw rare earths and tends to process them into industrial materials. So Japan is more dependent on the materials affected by China’s tightening quotas. 
 
 Advertisement Continue reading the main story 
 
 It was on Oct. 18 that the Chinese government broadened its halt in raw rare earths to include the United States and Europe. That step enabled customs officials to take the position that they were checking all rare earth shipments closely and were not singling out Japan. 
 
 The move also occurred only hours after Zhang Guobao, the country’s top energy official, summoned foreign reporters in Beijing. There, he delivered a blistering denunciation of the Obama administration’s decision the previous Friday to begin investigating whether China’s clean energy policies violated the World Trade Organization ’s free trade rules. But the exact interaction between American policy decisions and Chinese customs enforcement actions is unclear. 
 
 For China, the embargo on rare earth shipments has provided at least some geopolitical leverage. The halt was one of a series of measures that China took after Japan detained the captain of a Chinese fishing trawler that collided with two Japanese patrol boats; Japan later released the trawler’s captain. 
 
 Japanese companies had been able to weather the embargo without any significant factory shutdowns because many Japanese companies had accumulated rare earth stockpiles in the last few years. Still, the interruption of shipments caused dismay and alarm in the Japanese business community and Japan’s government. ||||| Moreover, the tight export quotas have caused world prices to soar, even while holding steady in China. 
 
 Photo 
 
 Officials in two departments of China’s General Administration of Customs in Beijing declined to comment on Thursday evening about the status of rare earth exports. The commerce ministry, which handles trade policy, also had no immediate comment. 
 
 Although deposits of rare earths are found in various parts of the world, including the United States, China produces about 95 percent of the global supply of the minerals. That is largely because rare earth mining and processing can be so environmentally risky, creating toxic and even radioactive wastes, that other countries have tended to avoid or abandon production. Only recently have other nations begun scrambling to develop or expand their own mining capabilities. 
 
 The Chinese shipments resumed Thursday morning only hours before Secretary of State Hillary Rodham Clinton raised the embargo issue at a news conference in Honolulu, where she announced plans to visit China on Saturday to pursue the matter with Chinese officials. 
 
 Mrs. Clinton spoke after meeting with Japan’s foreign minister, Seiji Maehara, and said that the suspension of shipments had been a “wake-up call” and that both countries would have to find alternative sources of rare earth materials. 
 
 Because China is on the opposite side of the international dateline from Honolulu, it was already midday on Thursday in China by the time Mrs. Clinton spoke in Honolulu on Wednesday. Later, after the New York Times Web site reported that the embargo had been lifted, an administration official said the United States was still seeking clarification from China. 
 
 In recent weeks, senior Chinese commerce ministry officials have insisted that they had not issued any regulations halting shipments. They have suggested at various times — implausibly, in the view of industry executives — that the halt resulted from a spontaneous and simultaneous decision by the country’s 32 authorized rare earth exporters not to make shipments, whether because of a deterioration in Sino-Japanese relations or a greater thoroughness on the part of customs inspectors. 
 
 Photo 
 
 Under this year’s quota — 30,300 metric tons of authorized shipments — only a few thousand metric tons remain to be exported in 2010. Meanwhile, annual demand outside China for raw rare earths approaches 50,000 tons, according to industry estimates. 
 
 Advertisement Continue reading the main story 
 
 The Chinese government assigns its quotas to the authorized exporters, who often trade those rights like commodities. As recently as 2008, the quota rights themselves had no market value. But lately, with rising demand, the value of the remaining quotas has soared to the point that the right to export a single ton of rare earths from China now sells for about $40,000, including special Chinese taxes . 
 
 That is a sizable, additional cost for buyers of neodymium, a rare earth used to make lightweight, powerful magnets essential to technologies including giant wind turbines , gasoline- electric cars and Apple iPhones. 
 
 Newsletter Sign Up Continue reading the main story Please verify you're not a robot by clicking the box. Invalid email address. Please re-enter. You must select a newsletter to subscribe to. Sign Up You will receive emails containing news content , updates and promotions from The New York Times. You may opt-out at any time. You agree to receive occasional updates and special offers for The New York Times's products and services. Thank you for subscribing. An error has occurred. Please try again later. View all New York Times newsletters. 
 
 Neodymium sells for about $40,000 a metric ton in China, having recovered from a nose-dive during the global economic crisis. But it sells for twice that much outside the country because of the export restrictions, according to data from Metal Pages, a database service in London . 
 
 The cost of quotas has become exorbitant for users of lanthanum, which is vital for the catalytic converters that clean the exhaust of conventional, gasoline-powered cars. It is mostly produced here in Baotou, a smoggy mining and steel city in China’s Inner Mongolia that is the capital of China’s rare earth industry. Lanthanum sells for less than $4,500 a ton in China, but up to 10 times that much outside China because of the export restrictions. 
 
 Such price differences have created a big incentive for companies to move factories to China, and many already have. 
 
 Photo 
 
 China’s shipping embargo has caused much more distress in Japan than in the United States or Europe, and not just because Japan’s shipments were cut off much earlier. It is because Japan tends to be affected more than other industrial nations by the way China sets its rare earth export quotas. 
 
 China’s quotas — and the shipping embargo — have involved only shipments in which the material has a rare earth content of about 50 percent or more. High-technology materials made from rare earths, like special magnetic powders for the clean energy and electronics industries, or polishing powders for the glass industry, are not subject to quotas and are inexpensively available. 
 
 Because the United States and Europe mainly buy highly processed rare earth powders from China, the customs policy of blocking shipments of raw rare earths had a limited, mostly symbolic effect. Japan, in contrast, is the biggest importer of raw rare earths and tends to process them into industrial materials. So Japan is more dependent on the materials affected by China’s tightening quotas. 
 
 Advertisement Continue reading the main story 
 
 It was on Oct. 18 that the Chinese government broadened its halt in raw rare earths to include the United States and Europe. That step enabled customs officials to take the position that they were checking all rare earth shipments closely and were not singling out Japan. 
 
 The move also occurred only hours after Zhang Guobao, the country’s top energy official, summoned foreign reporters in Beijing. There, he delivered a blistering denunciation of the Obama administration’s decision the previous Friday to begin investigating whether China’s clean energy policies violated the World Trade Organization ’s free trade rules. But the exact interaction between American policy decisions and Chinese customs enforcement actions is unclear. 
 
 For China, the embargo on rare earth shipments has provided at least some geopolitical leverage. The halt was one of a series of measures that China took after Japan detained the captain of a Chinese fishing trawler that collided with two Japanese patrol boats; Japan later released the trawler’s captain. 
 
 Japanese companies had been able to weather the embargo without any significant factory shutdowns because many Japanese companies had accumulated rare earth stockpiles in the last few years. Still, the interruption of shipments caused dismay and alarm in the Japanese business community and Japan’s government.
– China has resumed its shipment of rare earth minerals to the United States, after cutting us off early last week, the New York Times reports. Shipments to Japan, which have been suspended since September due to disputes involving the arrest of Chinese fishermen, also resumed, though they are facing some delays. The decision came hours after an announcement by Secretary of State Hillary Clinton that she would travel to China tomorrow to discuss the matter. She called the suspension a “wake-up call,” saying the US and Japan need to find alternate supplies of these materials. China, which produces 95% of the world's rare earth minerals, has repeatedly downgraded its export levels of these materials over the last five years; what it currently ships is well below world demand. Read the full article.