Using Quarry Rock Dust vs. Azomite in the Garden

Evaluating Local Rock Dust for Soil Amendment

Rock dust from local quarries can be an inexpensive mineral source—often $5-6 per ton compared to commercial products like Azomite. However, composition varies by quarry:

• Limestone quarry dust: Raises soil pH (alkaline), similar to agricultural lime. Beneficial only if your soil is too acidic.
• Silicate/igneous rock dust: Provides a broad spectrum of trace minerals without drastically altering pH. Excellent for remineralizing depleted soils.

Safety and Application

Before applying, verify the quarry source and request a mineral analysis. Avoid dust from quarries processing contaminated or industrial materials. Apply at 10-50 lbs per 100 sq ft, incorporated into the top 6 inches of soil. For detailed guidance, see the Rock Dust Primer from Remineralize.org.

While Azomite offers consistent, certified composition, local rock dust can be a cost-effective alternative if sourced responsibly.