Hydrothermal deposition

1)

Magma that has cooled and solidified within the Earth's crust form rocks called igneous intrusions.

2)

These intrusions produce pressurised superheated water at high temperatures. This dissolves many minerals from surrounding rocks.

3)

These mineral rich solutions travel along fissures, away from the igneous batholith, cooling as they do so.

4)

As they cool, dissolved minerals crystallise and come out of the solution.

5)

They do this in order of their solublity, with the least soluble crystallising first.

What does the process of fractional crystallisation start with?

It started with a mixture of minerals that could not have been exploited.

Once the minerals were separated and deposited (soon after the batholith formed) later exploitation became possible.

Name some metal ores that are deposited by hydrothermal processes

Tin, copper, lead, silver, gold, arsenic