sedimentary

Jasper

Silicon dioxide (SiO2)

Hardness: 6.5-7 (Mohs); Color: Reddish-brown, earthy tones; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Reddish-brown, earthy tones
Luster: Waxy to dull

Identified June 30, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Reddish-brown, earthy tones; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Formation & geological history

Formed through the deposition of silica in groundwater or hydrothermal fluids, often within volcanic ash or sedimentary basins. This specimen likely originates from the Precambrian or Paleozoic eras common in the crystalline and sedimentary belts near São Paulo, Brazil.

Uses & applications

Used primarily as an ornamental stone, in jewelry (cabs), lapidary art, and historically for stone tools due to its toughness and fracture pattern.

Geological facts

Jasper is an opaque variety of chalcedony. The location (near São Paulo, Brazil) is geologically diverse, featuring the Ribeira Belt and Paraná Basin, where silica-rich minerals like agate and jasper are commonly found as river-worn cobbles.

Field identification & locations

Identify by its hardness (cannot be scratched by a steel knife), smooth waxy feel when wet, and lack of transparency. Common in gravel beds and stream deposits in the state of São Paulo.