ock dust is a fine, powdery material mixed with aggregates typically screened to 3/8". It’s a byproduct of crushed rock and is commonly used as a compactable base. Suitable for use as a base layer in paddocks, pathways, and under pavers, it provides a solid, stable surface. Rock dust compacts well, drains adequately, and offers a cost-effective solution for leveling and finishing a variety of surfaces.