Submarine sand deposits are rich in deposits. From precious diamond, platinum sand, gold sand, to general cassiterite, magnetite, chromite, tungsten ore, and cheap gravel debris, there are more than 20 kinds. Undersea tin mining has become an important industry in Thailand, Indonesia, Malaysia and other countries. However, sand and gravel are the most mined from the shallow sea floor, with more than 500 million tons a year in the United States alone. In addition to being used in the production of glass, ceramics and grinding wheels, these gravel are mainly used as building materials, and some countries mine calcareous sand, shells and calcareous shale from the shallow sea floor as raw materials for cement production.
in line with the meaning of the original text?
Seabed tin mining has become a pillar industry in Southeast Asian countries