Rock Identifier
Red jasper (Jasper (microcrystalline quartz, SiO₂), iron-oxide-rich variety) — mineral
mineral

Red jasper

Jasper (microcrystalline quartz, SiO₂), iron-oxide-rich variety

AI-generated identification · may be incorrect

Opaque brick-red to reddish-brown, dull to slightly waxy luster, very fine-grained and massive; hardness about 6.5–7 Mohs, no cleavage, specific gravity roughly 2.6. The rough, dense appearance is consistent with jasper, though iron-rich chert or weathered volcanic rock is possible from a photograph alone.

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Physical properties

Opaque brick-red to reddish-brown, dull to slightly waxy luster, very fine-grained and massive; hardness about 6.5–7 Mohs, no cleavage, specific gravity roughly 2.6. The rough, dense appearance is consistent with jasper, though iron-rich chert or weathered volcanic rock is possible from a photograph alone.

Formation & geological history

Forms when silica-rich fluids replace or cement sediment, commonly incorporating hematite or other iron oxides; it may also occur as silicified volcanic or hydrothermal material. The specimen’s precise age cannot be determined visually.

Uses & applications

Used as an ornamental and lapidary stone for cabochons, beads, carvings, and polished pieces; occasionally as aggregate or decorative stone. A small rough fragment typically has modest value.

Geological facts

Its red color is produced mainly by dispersed hematite. Jasper is a variety of chert rather than a single mineral species.

Field identification & locations

Commonly found as dense red pebbles and nodules in gravel, sedimentary rocks, and hydrothermal zones. A steel file should barely scratch it; it may scratch glass, while dilute acid produces no fizz. Around 47.6°N, 19.3°E, red jasper or iron-stained chert is geologically plausible in transported gravels, but locality confirmation needs testing.