sedimentary

Sandstone with Manganese Dendrites

Clastic Sedimentary Rock (SiO2 based with MnO2 inclusions)

AI-generated identification · may be incorrect

Hardness: 6-7 (quartz-based); Color: Tan/grey background with dark brown to black banding; Luster: Dull/Earthy; Structure: Granular/Clastic; Cleavage: None

Hardness: 6-7 (quartz-based)
Color: Tan/grey background with dark brown to black banding
Luster: Dull/Earthy

Identified June 2, 2026More sedimentary →

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Physical properties

Hardness: 6-7 (quartz-based); Color: Tan/grey background with dark brown to black banding; Luster: Dull/Earthy; Structure: Granular/Clastic; Cleavage: None

Formation & geological history

Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments. The dark lines are likely mineral dendrites or manganese oxide staining that occurred when mineral-rich water seeped through cracks or pore spaces in the rock over geological time.

Uses & applications

Commonly used as a decorative garden stone, in landscaping, or as a teaching specimen for geological processes. High-quality dendritic stones are used in lapidary art.

Geological facts

While the dark lines often resemble fossilized plants or moss, they are purely inorganic mineral growth usually composed of manganese oxides. This specimen shows a water-worn, tumbled edge suggesting it was found near a river or beach.

Field identification & locations

Identify by its gritty texture (feels like sandpaper) and the distinct dark mineral patterns. Commonly found in riverbeds, canyons, and sedimentary basins worldwide. Collectors look for high contrast patterns.