Clay Posted on November 8, 2022August 1, 2023 by Tex Norwood The smallest type of soil particle (less than 0.002mm in diameter). Related Images:Related Articles: Perlite vs VermiculiteGuide to Coco Coir Growing MediaManure and Compost as Nutrient SourcesHow Soil Impacts the Health of Your PlumeriaGlossary: AggregationVisit our InfoTIP Glossary