The interaction of mineral dust with N₂O₅ was investigated using both airborne mineral aerosol (using an aerosol flow reactor with variable relative humidity) and bulk samples (using a Knudsen reactor at zero humidity). Both authentic (Saharan, SDCV) and synthetic dust samples (Arizona test dust, ATD and calcite, CaCO₃) were used to derive reactive uptake coefficients (γ). The aerosol experiments (Saharan dust only) indicated efficient uptake, with e.g. a value of γ(SDCV)=(1.3±0.2)×10⁻² obtained at zero relative humidity. The values of γ obtained for bulk substrates in the Knudsen reactor studies are upper limits due to assumptions of available surface area, but were in reasonable agreement with the AFT measurements, with: γ(SDCV)=(3.7±1.2)×10⁻², γ(ATD)=(2.2±0.8)×10⁻² and γ(CaCO₃=(5±2)×10⁻². The errors quoted are statistical only. The results are compared to literature values and assessed in terms of their impact on atmospheric N₂O_5.