Did you know that the price of metals can be determined by its crustal abundance in the earth. What is crustal abundance then? Crustal abundance of metals is how frequently it is found within the earth crust. As the crustal abundance of a metal rises its price falls. If a metal has a really low crustal abundance, like gold, then its price is higher. What is amazing about looking at crustal abundance is that it has stayed constant over the course of history. We see these same factors making the price of gold during roman times as we do in the modern day.
When we look at this relationship in a graph we need to use a log scale and view the prices and crustal abundance as log values. Changing the data to log values allows us essentially to view similar percentage changes and compare 2 different data sets percentage change even though they have radically different scales and numbers.