sedimentary (chemical)

Yellow Jasper

Silicon Dioxide (SiO2) with Goethite/Iron oxide impurities

Hardness: 6.5-7 (Mohs scale), Color: Mustard yellow to golden brown, Luster: Vitreous to waxy, Crystal Structure: Trigonal (Microcrystalline), Cleavage: None (Conchoidal fracture), Specific Gravity: 2.58-2.91

Hardness: 6

Identified March 8, 2026More sedimentary (chemical) →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich fluids in volcanic ash or sedimentary rock. Over millions of years, the silica crystallizes into microcrystalline quartz, with iron oxides like goethite providing the yellow hue. Most jasper formations range from the Precambrian to more recent geological eras.

Uses & applications

Primarily used for lapidary work, including cabochons for jewelry, decorative carvings, and as a highly valued material for rock tumbling. It is also a popular collector's stone due to its ability to take a high polish.

Geological facts

Jasper has been used as a gemstone since antiquity; the name is derived from the Greek word 'iaspis', meaning 'spotted stone'. It is exceptionally durable, which is why ancient peoples often fashioned it into tools as well as ornaments.

Field identification & locations

Identify in the field by its opaque nature (unlike translucent chalcedony), smooth conchoidal fracture, and inability to be scratched by a steel knife. Commonly found in riverbeds or volcanic regions in locations like Oregon (USA), Brazil, India, and Madagascar.

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Silicon Dioxide (SiO2) with iron oxide and hydroxide inclusions

sedimentary (chemically precipitated)

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Silicon Dioxide (SiO2) with iron oxide inclusions

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Jasper with Pyrite (Gold-colored inclusions)

Silicon Dioxide (SiO2) with Iron Disulfide (FeS2) inclusions

sedimentary (chemical/biological)

Jasper (Milky/Cream Variety)

Silicon Dioxide (SiO2) - variety of Chalcedony

sedimentary (chemical/biological)

Banded Calcite (Mexican Onyx)

Calcium Carbonate (CaCO3)

mineral

Green Jasper with Agate Banding

Silicon Dioxide (SiO2) with impurities of ferrous silicate or chlorite

sedimentary (chemical/biological origin)