Sandstone or Mudstone with Iron Staining

Physical Properties

Hardness varies (usually 2-6 on Mohs scale depending on cementation); color is often reddish, orange, or brown due to iron oxides (rust); dull or earthy luster; clastic sedimentary structure; no cleavage; specific gravity around 2.2-2.8.

Formation & Geological History

Formed by the accumulation and cementation of sand or mud-sized mineral grains, typically quartz and feldspar, in a variety of environments like rivers, lakes, or oceans. The red/orange color comes from oxidation of iron minerals (weathering).

Uses & Applications

Used locally as a building stone, in landscaping, or as aggregate. Not typically used in jewelry. Often collected for its aesthetic earthy colors.

Geological Facts

The reddish-brown staining is primarily hematite or limonite. These rocks are common worldwide and often form iconic landscapes in arid regions.

Field Identification & Locations

Identified by its grainy texture (if sandstone) or fine texture (if mudstone), typical reddish/rusty color, and relatively low hardness compared to igneous rocks. Found in sedimentary basins worldwide.

Identified on: 4/26/2026

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