metamorphic

Weathered iron-rich metamorphic rock, likely banded ironstone or quartzite

Ferruginous quartzite/itabirite; mainly quartz (SiO₂) with iron oxides such as hematite and goethite

AI-generated identification · may be incorrect

Brown, tan, and dark reddish mottling; dull to earthy luster and massive, fine-grained texture. Quartz-rich portions are typically Mohs 7, while iron-oxide coatings are softer; no obvious cleavage. Specific gravity commonly about 2.7–4.0 depending on iron content.

Identified September 7, 2026More metamorphic →

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At a glance

Common name: Weathered iron-rich metamorphic rock, likely banded ironstone or quartzite
Scientific name: Ferruginous quartzite/itabirite; mainly quartz (SiO₂) with iron oxides such as hematite and goethite
Category: metamorphic
Identified: September 7, 2026
Method: Standard

AI Estimated Value

About $1–$10 as a common hand specimen; perhaps $10–$30 if confirmed as attractive iron-rich quartzite or banded ironstone.

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 when quartz-rich sediment was metamorphosed and later oxidized during weathering. The specimen is probably Precambrian in age, consistent with iron-rich terrains around southeastern Brazil, though the photograph cannot establish age conclusively.

Uses & applications

Used as aggregate, building stone, and iron ore when sufficiently iron-rich; attractive pieces may be collected as lapidary or display specimens, though this one appears ordinary.

Geological facts

The dark patches may be hematite, magnetite, or manganese/iron staining rather than true banding. Southeastern Brazil contains extensive Precambrian metamorphic rocks and iron formations.

Field identification & locations

Check for a glassy quartz-like fracture, streak, and hardness: quartz-rich areas should scratch glass, while hematite gives a reddish-brown streak and magnetite is magnetic. A clearer identification requires a fresh break, streak test, magnet, and density measurement.