Mineral/Metamorphic Substrate

Gossan (Iron Hat) with Quartz and Chlorite

Limonite/Goethite-rich Gossan (FeO(OH)·nH2O) with inclusions of Quartz and Chlorite

AI-generated identification · may be incorrect

Hardness: Variable (Quartz 7, Iron oxides 5-5.5); Color: Rusty red, earthy brown, with green chlorite and translucent quartz; Luster: Earthy to vitreous; Structure: Massive/amorphous iron oxides with crystalline inclusions; Cleavage: None/unpredictable.

Hardness: Variable (Quartz 7, Iron oxides 5-5
Luster: Earthy to vitreous

Identified March 26, 2026More mineral/metamorphic substrate →

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At a glance

Common name: Gossan (Iron Hat) with Quartz and Chlorite
Scientific name: Limonite/Goethite-rich Gossan (FeO(OH)·nH2O) with inclusions of Quartz and Chlorite
Category: Mineral/Metamorphic Substrate
Identified: March 26, 2026
Method: Standard

AI Estimated Value

$5-$25 for handheld raw specimens; slightly higher if significant amounts of crystals (like clear quartz or vugs) are present.

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

Formed through the intense oxidation of sulfide ore deposits near the surface (the 'iron hat'). Rainwater reacts with mineral sulfides like pyrite, leaching away metals and leaving behind stable iron oxides, quartz, and secondary minerals like chlorite.

Uses & applications

Historically used as an indicator for miners to find deeper deposits of copper, gold, or silver. Today, primarily collected as geological specimens or used as low-grade iron ore in specific contexts.

Geological facts

Gossans are essentially 'rotted' rock. In many famous gold rushes, miners first discovered these rusty outcrops because the oxidation process often concentrates heavy gold particles as other minerals weather away.

Field identification & locations

Identify in the field by its distinct rusty, 'burnt' appearance and porous texture compared to surrounding rock. Common in old mining districts or areas with hydrothermal activity. Collectors look for unique mineral inclusions within the iron matrix.

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