Lava Rock with Fabric Impression

Physical Properties

Hardness: 5-6 (Mohs); Color: Dark brown to black; Luster: Dull to sub-vitreous; Structure: Vesicular/aphanitic; Features: Cross-hatch woven impressions remaining on the surface.

Formation & Geological History

Formed from the rapid cooling of mafic lava (basaltic) containing dissolved gases. This specific specimen indicates contact with a woven material, likely a man-made fabric or mat, while the lava was still plastic/molten.

Uses & Applications

Primarily of archaeological or novelty interest. Scoria is usually used in landscaping, gas grills, and high-temperature insulation.

Geological Facts

This specimen is unusual because it preserves the texture of a woven fabric ('lava casting'). It suggests the lava flowed over a man-made object or that a person pressed a material into the cooling rock.

Field Identification & Locations

Identify by looking for the bubbly (vesicular) texture of volcanic scoria combined with unnatural geometric patterns. Common in volcanic regions like Hawaii, Iceland, or Italy.

Identified on: 5/10/2026

Mode: Standard