Currently, some of the known deposits are mined by prospector cooperatives. |
Some areas are mined for the underlying gypsiferous materials that is used for making wall board. |
Here the island dips into a broad, shallow depression where guano was once mined. |
Insects mined and bored every bit of wood and leaf, while centipedes and millipedes crawled all over. |
By 1952 an improved grade of ore was encountered, and the lode was mined until 1956, when ore reserves were exhausted. |
Other mined materials include iron from ferrous sulphate, copper, and molybdenum. |