• Composition: They contain economically valuable metals such as copper, zinc, lead, iron, silver, gold, and platinum.
• Formation: PMS form when seawater penetrates the oceanic crust, gets heated by magma, dissolves metals, and then releases them through hydrothermal vents where they precipitate as sulphides.
• Location: Commonly found at mid-ocean ridges, back-arc spreading centres, and volcanic margins; these deposits are usually associated with tectonic activity.
• Economic importance: They are rich sources of metals crucial for electronics, construction, and renewable energy industries, increasingly important as terrestrial mineral resources deplete.
• Environmental considerations: Mining these deposits poses challenges such as habitat destruction, toxic substance release, and sea floor disruption, necessitating environmentally responsible mining practices.
• Deposits vary in size from thousands to millions of tonnes, with some deposits still largely undiscovered due to limited exploration of oceanic ridges.

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