metamorphic

Weathered iron-stained quartzite or chert nodule

Siliceous rock composed chiefly of microcrystalline quartz (SiO₂), with iron-oxide staining and possible clay/minor carbonate minerals

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; cream, tan, reddish-brown, and gray colors; dull to waxy luster; massive, fine-grained texture with irregular fracture and no obvious cleavage. The porous cavities and rusty staining suggest strong weathering or partial replacement, so exact identification from the image is limited.

Identified August 31, 2026More metamorphic →

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At a glance

Common name: Weathered iron-stained quartzite or chert nodule
Scientific name: Siliceous rock composed chiefly of microcrystalline quartz (SiO₂), with iron-oxide staining and possible clay/minor carbonate minerals
Category: metamorphic
Identified: August 31, 2026
Method: Standard

AI Estimated Value

About $2–$15 as an ordinary hand specimen; up to roughly $20–$50 if unusually attractive, locality-labeled, or confirmed as a distinctive mineralized specimen.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Likely formed from silica-rich sediment that lithified and/or recrystallized, then acquired iron staining and surface cavities during weathering; its geological age cannot be determined visually. Similar material occurs in weathered sedimentary and metamorphic terrains worldwide.

Uses & applications

Usually a collector specimen, landscaping stone, or teaching sample; sound quartzite can be used as aggregate and building stone, but this irregular weathered piece has little commercial value.

Geological facts

The red-brown colors commonly come from hematite and goethite rather than the primary rock. A steel file should barely scratch it, while glass may be scratched by a fresh surface.

Field identification & locations

Look for a very hard silica-rich body, granular or waxy fracture, and rusty iron-oxide coatings; acid testing and a fresh broken surface help distinguish quartzite from chert, jasper, or weathered carbonate rock. Common in quartz-rich mountain belts and gravel deposits.