Average particle size of powdered gold is:

A fine powder is formed by chemical precipitation or by atomizing the metal. The particle sizes vary (average 15 µm). The pellets are mixed with soft wax (0.01% organic wax, which is burnt off prior to use) and then wrapped with gold foil (No. 3), rather than sintering the mass, like for mat gold. Ref: Basic Dental Materials 4th ed page no 160