Rock Identifier
Jasper (likely brecciated or silicified jasper) (Microcrystalline quartz/chalcedony, SiO₂, colored mainly by iron oxides) — sedimentary
sedimentary

Jasper (likely brecciated or silicified jasper)

Microcrystalline quartz/chalcedony, SiO₂, colored mainly by iron oxides

AI-generated identification · may be incorrect

Opaque reddish-brown, cream, and gray material with earthy to dull vitreous luster; quartz hardness is about 6.5–7 Mohs, with no visible cleavage and conchoidal fracture. The irregular color patches suggest brecciation, veining, or surface weathering.

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Physical properties

Opaque reddish-brown, cream, and gray material with earthy to dull vitreous luster; quartz hardness is about 6.5–7 Mohs, with no visible cleavage and conchoidal fracture. The irregular color patches suggest brecciation, veining, or surface weathering.

Formation & geological history

Jasper forms when silica-rich fluids cement or replace sediments, volcanic material, or fractures, while iron oxides produce red and brown colors. Its precise age cannot be determined from the photograph; deposits range from Precambrian to recent.

Uses & applications

Used for cabochons, beads, carvings, ornamental stone, and lapidary work; massive material has limited architectural use. Value is usually modest unless the pattern, polish, or locality is exceptional.

Geological facts

Jasper is a rock rather than a single mineral and commonly grades into chert, agate, and chalcedony. Red coloration generally reflects hematite or related iron minerals.

Field identification & locations

Identify it by its opaque patterned body, waxy-to-dull luster, lack of cleavage, and inability to scratch glass only if sufficiently quartz-rich; a steel knife generally will not scratch fresh jasper. Common sources include India, Madagascar, Brazil, Australia, Mexico, and the western United States.