metamorphic

Iron-rich metamorphic rock, likely banded iron formation fragment

Banded iron formation (BIF), chiefly hematite–magnetite with chert; exact identification requires testing

AI-generated identification · may be incorrect

Dark gray to rusty brown, metallic-to-earthy luster, irregular fracture, and dense/heavy appearance; hardness commonly 5–6.5 (hematite/magnetite) with no obvious cleavage. The reddish-brown areas suggest iron oxides from weathering; magnetism may be present.

Identified September 1, 2026More metamorphic →

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At a glance

Common name: Iron-rich metamorphic rock, likely banded iron formation fragment
Scientific name: Banded iron formation (BIF), chiefly hematite–magnetite with chert; exact identification requires testing
Category: metamorphic
Identified: September 1, 2026
Method: Standard

AI Estimated Value

Typically $5–$30 for an ordinary hand specimen; attractive banded or highly magnetic pieces may sell for $30–$100+.

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

BIF formed when dissolved iron precipitated with silica in ancient marine environments, mainly during the Precambrian roughly 3.8–1.8 billion years ago; oxidation produces the rusty surface.

Uses & applications

Used as iron ore where sufficiently rich; otherwise collected as a geological specimen or occasionally cut and polished for decorative stone.

Geological facts

A strong magnet, red-brown streak (hematite), or black streak and high magnetism (magnetite) would help distinguish its mineral content. The photograph does not clearly show diagnostic banding, so it could also be iron-rich schist or massive hematite.

Field identification & locations

Common in Precambrian shield regions such as Minnesota, Michigan, Western Australia, Brazil, India, and South Africa. Check density, streak, and magnetism; avoid assuming identity from color alone.