Cornwall Minerals Railway ended in 1896.
Cornwall Minerals Railway was created in 1873.
The subsoil becomes rich in minerals as minerals from the topsoil leach down into the subsoil.
Water would be full of minerals. Also anything that contains water would be rich in minerals. For example orange juice. Fish is another good example of food that would be rich in minerals.
Eastern Asia is rich with minerals.
Hades is very rich with the Earth's minerals.
Cornwall WAS rich in tin but there isn't much left now and most of the mines have closed.
Minerals
Soil rich in minerals deposited by flooding rivers is called silt.
The area itself is actually not a good place to do rock and mineral collecting, but you can look near bodies of water or lower ground for good minerals.
Both humus and minerals contain nitrogen for growth of plants. Alluvial soils are rich in humus and minerals making them good for growth of plants.
Volcanic islands have a rich supply of minerals because when a volcano erupts it produces lava (magma) and that lava has lots of rocks and minerals in it.