We have developed a characterization method adapted to granular products based on conventional rheological techniques. We have used glass beads as model powders. By submitting a bed of glass beads to vertical vibrations, we have created conditions that can be seen as an equivalent Brownian motion at a macroscopic scale. We have obtained rheograms in both 'steady-state' and 'dynamic' regimes that can be interpreted in terms of equivalent viscosity and equivalent elastic and viscous moduli. In addition, we have shown that a solid-liquid transition can be observed depending on the vertical vibration frequency, in other term on the so-called granular temperature.