Rock Identifier
Jasper (specifically Polychrome or Desert Jasper) (Silicon Dioxide (SiO2) with iron oxide and other mineral impurities) — sedimentary (chemical/biological origin)
sedimentary (chemical/biological origin)

Jasper (specifically Polychrome or Desert Jasper)

Silicon Dioxide (SiO2) with iron oxide and other mineral impurities

Hardness: 6.5-7 on Mohs scale. Color: Multicolored (red, yellow, brown, grey). Luster: Vitreous to waxy. Crystal structure: Cryptocrystalline (microscopic quartz crystals). Cleavage: None (conchoidal fracture). Specific gravity: 2.58-2.91.

Hardness
6
Color
Multicolored (red, yellow, brown, grey)
Luster
Vitreous to waxy
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Physical properties

Hardness: 6.5-7 on Mohs scale. Color: Multicolored (red, yellow, brown, grey). Luster: Vitreous to waxy. Crystal structure: Cryptocrystalline (microscopic quartz crystals). Cleavage: None (conchoidal fracture). Specific gravity: 2.58-2.91.

Formation & geological history

Formed when silica-rich fluids permeate volcanic ash or sedimentary rock, slowly replacing organic or mineral matter while retaining high concentrations of iron oxides. These typically date from the Jurassic to the Tertiary periods.

Uses & applications

Predominantly used for lapidary work, jewelry (cabochons), ornamental carvings, and as decorative rough for rock collectors.

Geological facts

Jasper has been used by ancient civilizations for thousands of years to create seals and amulets. The name 'Jasper' is derived from the Greek word 'iaspis', meaning 'spotted stone'. It is an opaque variety of chalcedony.

Field identification & locations

Identify in the field by its smooth, shell-like (conchoidal) fracture surfaces and its inability to be scratched by a steel knife. It is commonly found in the deserts of Madagascar, Oregon, and the Southwestern United States. Collectors should look for vibrant banding and lack of transparency.

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Other sedimentary (chemical/biological origin) specimens

Green Jasper with Agate Banding (Silicon Dioxide (SiO2) with impurities of ferrous silicate or chlorite) — sedimentary (chemical/biological origin)

Green Jasper with Agate Banding

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

sedimentary (chemical/biological origin)
Red Jasper (Plum or Brick variety) (Silicon Dioxide (SiO2) with iron oxide inclusions (Hematite)) — sedimentary (chemical/biological origin)

Red Jasper (Plum or Brick variety)

Silicon Dioxide (SiO2) with iron oxide inclusions (Hematite)

sedimentary (chemical/biological origin)
Jasper (Wonderstone/Banded Jasper) (Silicon Dioxide (SiO2) with iron oxide impurities) — sedimentary (chemical/biological origin) or volcanic-related metamorphic

Jasper (Wonderstone/Banded Jasper)

Silicon Dioxide (SiO2) with iron oxide impurities

sedimentary (chemical/biological origin) or volcanic-related metamorphic
Chert (and Flint) (Silicon Dioxide (SiO2)) — sedimentary

Chert (and Flint)

Silicon Dioxide (SiO2)

sedimentary
Limestone (specifically Marl or Chalk) (Calcium Carbonate (CaCO3)) — sedimentary

Limestone (specifically Marl or Chalk)

Calcium Carbonate (CaCO3)

sedimentary
Note: Item is not a geological specimen (Homo sapiens (Dermal Appendage: Pilus)) — Organic / Biological

Note: Item is not a geological specimen

Homo sapiens (Dermal Appendage: Pilus)

Organic / Biological