Rock Identifier
Red jasper (iron-rich chert), possibly weathered hematite-rich material (Jasper: microcrystalline quartz (SiO₂) with iron-oxide inclusions; hematite: Fe₂O₃) — mineral
mineral

Red jasper (iron-rich chert), possibly weathered hematite-rich material

Jasper: microcrystalline quartz (SiO₂) with iron-oxide inclusions; hematite: Fe₂O₃

AI-generated identification · may be incorrect

Opaque dark red to maroon, earthy to dull/waxy luster, cryptocrystalline structure, no visible cleavage, and typically Mohs hardness 6.5–7; the crumbly surface may reflect weathering or matrix. The image alone cannot confirm whether hematite dominates.

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Physical properties

Opaque dark red to maroon, earthy to dull/waxy luster, cryptocrystalline structure, no visible cleavage, and typically Mohs hardness 6.5–7; the crumbly surface may reflect weathering or matrix. The image alone cannot confirm whether hematite dominates.

Formation & geological history

Jasper forms when silica-rich groundwater replaces or cements sediment, with iron oxides producing the red color; it commonly forms in Precambrian volcanic-sedimentary environments. Hematite-rich varieties develop through oxidation of iron-bearing minerals.

Uses & applications

Used as ornamental stone, beads, cabochons, carvings, and occasionally aggregate or pigment; attractive jasper has modest lapidary value.

Geological facts

Red color generally comes from finely disseminated hematite or goethite rather than red quartz. A streak test helps distinguish it: jasper usually leaves a weak white streak, while hematite leaves a red-brown streak.

Field identification & locations

Common in iron-rich soils, volcanic terrains, and sedimentary iron formations worldwide. Test an inconspicuous area for hardness against glass and streak on unglazed ceramic; avoid assuming identification from color alone.