Question

why do we need to conserve mineral resources?

Answer 1

I think .....
Some minerals are useful in industrial, agriculture and domestic uses. Minerals are nonrenewable resource and with increase in demand such minerals are getting depleted and their cost would increase spirally. 
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Hope it helps

Answer 2

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◆Continued extraction of ores leads to increasing costs as mineral extraction comes from greater depth.Its quality also decreases.

◆It took millions of years for creation of mineral resources and it may result in shortage in near future because of the fast consumption of minerals.