Spellstone (AKA magicite) is a quartz-like crystal that can store patterned anima. It comes in various forms, depending on the source and the levels of refinement. Charging a spellstone consumes a spell slot--the more powerful the slot the greater the effect. When a spellstone is used, it crumbles to dust.

These are the changes I usually make when DM'ing. Other than the racial restrictions these are not setting specific.