sedimentary

Sandstone (Pet Rock)

Clastic sedimentary rock (primarily SiO2)

AI-generated identification · may be incorrect

Hardness: 6-7 (Mohs); Color: Tan/Brown/Grey; Luster: Dull/Earthy; Structure: Granular/Clastic; Specific Gravity: 2.2-2.8. Note: Anthropomorphic facial features added with pigment/ink.

Hardness: 6-7 (Mohs)
Color: Tan/Brown/Grey
Luster: Dull/Earthy

Identified March 22, 2026More sedimentary →

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Physical properties

Hardness: 6-7 (Mohs); Color: Tan/Brown/Grey; Luster: Dull/Earthy; Structure: Granular/Clastic; Specific Gravity: 2.2-2.8. Note: Anthropomorphic facial features added with pigment/ink.

Formation & geological history

Formed through the accumulation and cementation of mineral particles (sand-sized grains), typically in riverbeds, deserts, or marine environments. The age varies by deposit location, ranging from recent to billions of years old.

Uses & applications

Used primarily as decorative art, novelty gifts, or paperweights. In unpainted form, sandstone is widely used in construction and landscaping.

Geological facts

This specimen is an example of a 'Pet Rock,' a 1970s cultural phenomenon. The markings are not geological but represent pareidolia—the human tendency to see faces in inanimate objects.

Field identification & locations

Identify in the field by its gritty texture (feels like sandpaper) and visible sand grains. These are commonly found in arid regions, beach environments, and river basins worldwide.