the growth of South Korea's automobile industry was the result of a surge in exports; 1989 exports, however, declined 28.5 percent from 1988. This decline reflected sluggish car sales to the United States, especially at the less expensive end of the market, and labor strife at home. South Korea today has developed into one of the world's largest automobile producers. The Hyundai Kia Automotive Group is South Korea's largest automaker in terms of revenue, production units and worldwide presence. Mining Most of the mineral deposits in the Korean Peninsula are located in North Korea, with the South only possessing an abundance of tungsten and graphite. Coal, iron ore, and molybdenum are found in South Korea, but not in large quantities and mining operations are on a small scale. Much of South Korea's minerals and ore are imported from other countries. Most South Korean coal is anthracite that is only used for heating homes and boilers. In 2019, South Korea was the 3rd largest world producer of bismuth, the 4th largest world producer of rhenium, and the 10th largest world producer of sulfur. Construction Construction has been an important South Korean export industry since the early 1960s and remains a critical source of foreign currency and invisible export earnings. By 1981 overseas construction projects, most of them in the Middle East, accounted for 60 percent of the work undertaken by South Korean construction companies. Contracts that year were valued at US$13.7 billion. In 1988, however, overseas construction contracts totaled only US$2.6 billion (orders from the Middle East were US$1.2 billion), a 1 percent increase over the previous year, while new orders for domestic construction projects totaled US$13.8 billion, an 8.8 percent increase over 1987. South Korean construction companies therefore concentrated on the rapidly growing domestic market in the late 1980s. By 1989 there were signs of a revival of the overseas construction market: the Dong Ah Construction Company signed a US$5.3 billion contract with Libya to build the second phase (and other subsequent phases) of Libya's Great Man-Made River Project, with a projected cost of US$27 billion when all 5 phases were completed. South Korean construction companies signed over US$7 billion of overseas contracts in 1989. Korea's largest construction companies include Samsung C&T Corporation, which built some of the highest building's and most noteworthy skyscrapers such as three consecutively world's tallest buildings: Petronas Towers, Taipei 101, and Burj Khalifa. Armaments During