Concept: Magic Stones
On this fantasy world only one form of magic exists. Magical stones.
For some reason these rocks have contained energy which can be unleashed to spectacular results. While rare, they can be mined, and are found similarity to other ores, though large veins are unheard of.
There are many different types of stones, each providing a different type of magical effect.
Red provides control over fire, dark blue over water, light blue over air, green over vegetation, black over decay, amber over containment, white over healing, etc.
These rocks when refined and cut in specific styles the power potential greatly increases.
People who specialize in knowledge, control, mining, and crafting / cutting of the rocks are called wizards.
Without training a person would have difficulties unleashing the power of the rocks and controlling it. This has potential to cause great tragedy and most people will simply shy away from even getting close to such a rock for fear of what may happen.
A wizard can control the power of the rocks through physical contact, and they can also be forged into objects such as weapons, armor, and jewelry. Though some crafty wizards build them into everyday objects to give them a life of their own and/or to provide wards or guards.