Question

why gold is so precious not iron?

Answer 1

Availability and extraction are the reasons for the cost of the minerals and metals.

Gold ores are very rare in the earths crust. The extraction of gold is costly process and % of gold from 1 kg of ore is very less. This makes it into high cost.

Diamonds are much rare in earths crust. Finishing and cutting of Diamond is too expensive because of which its cost is high

Answer 2

because it has lustre, for thi purpose it used for making jwellery
it is most malleable and ductile metal