mineral

Jasper

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Red, orangish-brown, or reddish-pink; Luster: Dull to waxy; Crystal Structure: Trigonal (microcrystalline/cryptocrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.91

Hardness: 6
Color: Red, orangish-brown, or reddish-pink
Luster: Dull to waxy

Identified June 29, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich fluids in volcanic rocks, sedimentary environments, or as a replacement in hydrothermal processes. Often associated with Cretaceous-age formations in Central Texas (the reported coordinate region), where it is frequently found as river-worn nodules.

Uses & applications

Popular for lapidary work, jewelry (cabochons), river rock landscaping, and as a semi-precious collector's stone. Historically used for making tools due to its conchoidal fracture.

Geological facts

Jasper is an opaque variety of chalcedony. The red color is typically caused by iron inclusions (hematite). It has been used for thousands of years throughout human history for seals and ornaments.

Field identification & locations

Identify in the field by its opacity (unlike translucent agate), its hardness (it will scratch glass), and its smooth, waxy surface when wet. Common in gravel beds and riverbanks across Central and East Texas.