Abstract: An air concentrator for dry separation of gold and other heavy minerals from alluvial deposits comprises a housing having a number of open-topped chambers arranged in a ring-like configuration and surmounted by a screen having rings thereon forming annular arms radiating from a hub sweeps over the screen beds. Air under pressure is fed sequentially and cyclically to the chambers by a rotary valve located centrally of the ring of chambers. The deposit is fed over the hub and is swept outwardly over the beds on the screen by the wiper arms, where it is fluidized by pulses of air from the subjacent chambers enabling particles of gold and heavy minerals to settle down to the bottom of the beds by gravitational stratification, and if sufficiently small, pass through the screen for collection through spigots in the bottom of the chambers.