You're right! Plato C. thought philosopher-kings should run the government.
In Plato's Republic, Plato argues that the ideal rule is by a philosopher-king who has stepped outside the cave, seen the light and come back to with this understanding to the cave to rule (see Cave metaphor).
The situation prevailing in a market in which buyers and sellers are so numerous and well informed that all elements of monopoly are absent and the market price of a commodity is beyond the control of individual buyers and sellers.
Demand for minerals increased after America shifted from Agrarian society to an industrial society.
Explanation:
After industrial revolution use of machines were extensive and huge which made mining possible. America is rich in minerals and metal resources huge hydraulic furnaces are used in mines in order to scarp out the silver, gold and copper which were available in abundance in America.
Mining had been active and much sought after at colonial times and after independence too. Gold rush in California made many mining facilities to be opened in America. Silver coinage promoted the silver mining industries in excavating out silver.