A Crucial Item

Power Stones
Power stones are what allow Petralists, Builders, and Stone Sculptors use to access their fantastical abilities. In The Petralist series universe ordinary rocks hold the keys to supernatural abilities for certain individuals. There are three types of people who can access these magical powers: Petralists, Builders, and Stone Sculptors.

Petralists
Petralists are able to sense then absorb power stones through physical contact to gain magical powers. This is called "tapping" and is not an immediate process. However, the more power that is harnessed from the stone the quicker the stone is exhausted of magical power until it's depleted or totally gone. For example a Petralist that "taps" Granite will gain super strength & stone-hard skin. Petralists are powerful individuals capable of using arcane power stones to enhance their physical and mental abilities as well as controlling the elements.

Builders
Builders are able to manifest the qualities of a power stone that cause a physical action/change in the stone and/or the environment. They "activate" the latent magical potential in power stones for a variety of effects through physical contact or remotely. For example a Builder that "activates" Granite will cause that stone to manifest it's magical strength-enhancing qualities, making that granite as hard as steel. Builders are very creative and possess an intuitive sense on how to use power stones to build fantastical machines. They mainly use their powers to create magic devices called "mechanicals".

Stone Sculptors
Possibly the rarest of the three types, Stone Sculptors are acutely attuned to sensing the magical power within power stones. Through this connection they are able to sculpt stone into impressively intricate, detailed, and beautiful artwork. For Stone Sculptors the sculpting process also involves the enhancement/enchantment of the power stone. Sculpting refines,purifies, and increases a stone's magical power. Stone Scupltors do not possess any outright fantastical magical abilities. Yet they can affect both Builder and Petralists to a certain extant as they can make power stone consumables more (or possibly less) effective.