Sandstone (with Iron Siderite Concretion)

Physical Properties

Hardness: 6-7 (for the quartz grains); Color: Gray-brown to tan; Luster: Dull/Earthy; Structure: Clastic, granular texture with concentric layering; Specific Gravity: 2.3-2.6.

Formation & Geological History

Formed by the precipitation of mineral cement (like iron oxide or calcite) within the spaces between sediment grains, often around a nucleus. Highly common in Paleozoic to Cenozoic rock beds.

Uses & Applications

Used primarily as decorative garden stones or geological teaching specimens. Larger sandstone deposits are used in construction and glassmaking.

Geological Facts

These are often mistaken for fossilized eggs or meteorites due to their rounded, symmetrical shapes and layered internal structures.

Field Identification & Locations

Identify in the field by looking for rounded edges that differ from the surrounding bedding, often harder than the host rock. Found globally in riverbeds and eroded cliffs.

Identified on: 4/20/2026

Mode: Standard