edginessand

Edginessand is a descriptor used in geology and civil engineering to refer to sands composed predominantly of grains with sharp, angular edges and rough surfaces. The term emphasizes grain shape over mineral composition, though quartz is commonly the dominant mineral. Angularity arises from mechanical fragmentation, limited transport, or rapid deposition, and contrasts with well-rounded sands formed by prolonged abrasion in fluvial or aeolian systems.

Grain morphology and measurement: Edginessand grains exhibit facets and non-spherical shapes with high surface roughness. Shape is often described using angularity and sphericity indices, and can be assessed through image analysis or qualitative grain-count methods. Compared with rounded sands, edginessand typically shows lower packing density and higher internal friction, which can affect strength and stability in geotechnical applications while also influencing workability in concrete and asphalt mixes.

Occurrence and environments: Edginessand occurs in proximal source zones such as talus cones, quarry dumps, and rapid depositional settings where limited transport preserves sharp edges. It can be found in fluvial deposits near bedrock, glacial outwash with short transport distances, and certain volcanic or lithic-rich sediments.

Engineering implications: In geotechnical design, edginessand affects compaction behavior, permeability, and filtration characteristics. The increased interlock from angular grains can raise shear strength in loose fills but may reduce workability in concrete and increase wear on equipment during handling and processing. The term is not part of formal sedimentology nomenclature and is used chiefly in niche studies and practical reports to describe distinctive grain shape.