One example of this from the past is aluminum. In the 1850s, it was extremely rare and difficult to produce - costing more than gold, used as serving utensils i

One example of this from the past is aluminum. In the 1850s, it was extremely rare and difficult to produce - costing more than gold, used as serving utensils in Napoleon's court, and as the capstone of the Washington monument. Now it's one of the cheapest metals.