Some sample questions from this category:
* Number 2 on the Mohs scale is represented by what?
* This mineral holds number 4 on the Mohs scale. It can be clear, blue, yellow, green, or purple. What is it called?
* This gemstone is high at number 8 in the Mohs scale. What is its name?
* The hardest mineral on Earth! At number 10, we have what?
* Number 6 is represented by orthoclase. Hematite, a naturally shiny black stone, also has a hardness of 6. What color is it when sliced thin or ground into powder?