Hawaii's mining products include: sand, gravel, stone, portland cement and masonry cement, plus gemstones, according to City-Data. At the beginning of the 21st Century, the value of these non-fuel minerals was approximately $70 million. In 2001, crushed stone was worth the most at $51.9 million, followed by portland cement at $10.2 million. Most of Hawaii's minerals are used in construction projects on the islands.
In 2003, the value of these construction minerals was $74 million. Encyclopedia.com explains approximately 600,000 metric tons of construction sand and gravel was produced in that year, while 6.5 million metric tons of crushed stone was mined. The crushed stone alone was valued at $66.6 million.
Huge manganese deposits exist underneath the Pacific Ocean from California to Hawaii. Nickel and cobalt are also found in these manganese deposits. Hawaii expects to see an employment boom from these deposits with technicians, geologists and scientists. Future revenues from these natural resources can bring an economic boost of $100 million from Chinese companies, according to Pacific Business News. In the late 1990s, foreign companies invested between $2 and $3 million to mine manganese south of the Big Island and 15,000 feet under the surface of the ocean.
There are no coal mines in Hawaii. The U.S. Energy Information Administration states there is just one coal-fired power plant in the entire island chain.