mineral

Polished magnetite-rich ironstone (probable magnetite/hematite nodule)

Magnetite, Fe₃O₄, possibly mixed with hematite, Fe₂O₃, and iron-bearing gangue

AI-generated identification · may be incorrect

Dark steel-gray to black, metallic-to-submetallic luster, unevenly polished surface, opaque, and likely strongly magnetic; magnetite hardness 5.5–6.5 Mohs, cubic crystal structure, no cleavage, specific gravity about 5.2. Exact identification requires a magnet and streak test.

Identified September 13, 2026More mineral →

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At a glance

Common name: Polished magnetite-rich ironstone (probable magnetite/hematite nodule)
Scientific name: Magnetite, Fe₃O₄, possibly mixed with hematite, Fe₂O₃, and iron-bearing gangue
Category: mineral
Identified: September 13, 2026
Method: Standard

AI Estimated Value

Approximately $5–$25 for a small common polished specimen; exceptional natural lodestones or provenance-rich pieces may be worth $50–$200.

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 by oxidation, hydrothermal alteration, or concentration of iron minerals in a volcanic or metamorphic host; age cannot be determined from the photograph. Rounded shape may reflect natural weathering or human polishing.

Uses & applications

Used historically as iron ore and pigment source; attractive polished pieces are sold as mineral specimens or curiosities, but this example is not suitable for jewelry without secure mounting.

Geological facts

Magnetite is naturally magnetic and can produce lodestone. Hematite-rich material commonly develops reddish-brown streak despite its black appearance.

Field identification & locations

Test with a strong magnet, inspect the streak on unglazed porcelain, and compare density; magnetite gives a black streak, while hematite gives red-brown. Common localities include Sweden, Russia, South Africa, the United States, and Mexico.