sedimentary

Weathered jasper/chert nodule

Microcrystalline quartz (SiO₂), likely iron- and clay-stained jasper or chert

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque, waxy to dull luster, reddish-brown, cream, green, and gray colors with irregular fracture and no visible cleavage. The mottled surface and hard silica-rich texture are consistent with jasper/chert, though the photograph limits certainty.

Identified August 8, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater replaces or cements sediment, commonly producing nodules and brecciated, iron-stained patterns; ages vary widely from Precambrian to Cenozoic depending on the deposit.

Uses & applications

Used as decorative stone, cabochons, carvings, lapidary material, and occasionally crushed aggregate. Quality depends on pattern, polishability, and rarity.

Geological facts

Jasper is an opaque variety of chalcedony or microcrystalline quartz; green coloration may reflect chlorite, clay minerals, or other inclusions rather than a single diagnostic mineral.

Field identification & locations

Look for a very hard, noncleavable surface that scratches glass and shows a smooth waxy fracture; a streak test is usually white to pale. Common worldwide in volcanic, hydrothermal, and sedimentary settings; acid produces no fizz unless carbonate contamination is present.