A handheld x-ray analyzer, having an outer shell forming an inner cavity, the outer shell having at least one aperture; an x-ray engine positioned within the cavity; and a generally planar heat sink rigidly and thermally attached to the x-ray engine, and positioned in the aperture of the outer shell thereby substantially filling the aperture while providing thermal conduction between the engine and surrounding air. An outer face of the heat sink may be substantially conformal with the outer shell along one or both sides of the analyzer, and form a substantial portion of one or both sides of the analyzer. Longitudinal fins may be placed on an outer face of the heat sink to aid in thermal conduction from the engine to the surrounding air. Thermal handling, shock/vibration isolation, and moisture barriers are provided.