water
Hardness and streak color are very important. The color of the mineral helps some, as well.
For Health e.g. calcium and iron.
Iron, Fe2+
Olivine is the most common mineral in the Earth's mantle.
Gold and salt
Pennsylvania's most important mineral is coal. Second is oil.
Carbonates are the second most important mineral group.
mineral oil
Calcium is the most important mineral for healthy bones, especially for women.
iron
Gravel
Calcium
Gold
Silicates
Bauxite
It is gold.
Pyrite, iron sulfide is a common mineral in many rocks. Pyrite is the most important sulfur-containing mineral.