metamorphic

Banded iron formation (ironstone), likely hematite–magnetite-rich

Banded iron formation (BIF), composed chiefly of hematite (Fe₂O₃), magnetite (Fe₃O₄), and microcrystalline quartz (SiO₂)

AI-generated identification · may be incorrect

Hardness about 5.5–6.5; metallic to submetallic gray-black surfaces with rusty red-brown iron-oxide bands; fine-grained, dense, and commonly weakly magnetic if magnetite-rich. The specimen shows elongated, folded or streaked banding rather than visible crystals.

Identified September 9, 2026More metamorphic →

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At a glance

Common name: Banded iron formation (ironstone), likely hematite–magnetite-rich
Scientific name: Banded iron formation (BIF), composed chiefly of hematite (Fe₂O₃), magnetite (Fe₃O₄), and microcrystalline quartz (SiO₂)
Category: metamorphic
Identified: September 9, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a common hand specimen; $30–$150 or more for large, highly polished, strongly banded, or locality-labeled pieces.

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 basins, mainly during the Precambrian roughly 3.8–1.8 billion years ago; later metamorphism compacted and deformed the layers. Oxidation produces the reddish-brown hematite and goethite coloration.

Uses & applications

Important iron ore when sufficiently rich, and commonly used as lapidary material, ornamental stone, and mineral-collection specimens. Polished pieces display attractive metallic and red banding.

Geological facts

BIF is a major record of Earth’s early oxygenation and supplied much of the world’s iron. A streak test may be red-brown for hematite or black for magnetite; a magnet can reveal magnetite-rich zones.

Field identification & locations

Common in Precambrian shield regions, including Australia, Brazil, India, South Africa, Canada, and the Lake Superior district. Field identification relies on distinctive iron/silica banding, high density, and possible magnetism; this hand specimen appears strongly metamorphosed or deformed.