A fluid diffuser system includes volcanic rock material positioned in a receptacle or within a gas-permeable filter. Airflow can be driven through the diffuser system, such as through the filter, to add droplets or vapors of fluids (e.g., aromatic fluids such as essential oils) to the airflow and then into the surrounding atmosphere of the system. The rock material can be highly porous to retain fluids in a natural, environmentally-friendly, and sustainable manner. Some systems are wearable and can use movement of the system to drive air past the rock material, and some systems can employ an air mover (e.g., fan) to drive airflow.