sedimentary

Jasper-Agate (Iron-stained Quartz)

Silicon Dioxide (SiO2) with iron oxide inclusions

AI-generated identification · may be incorrect

Hardness: 6.5-7 Mohs; Color: Tan, yellow-orange, and cream with brown iron staining; Luster: Waxy to vitreous when wet; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Hardness: 6
Color: Tan, yellow-orange, and cream with brown iron staining
Luster: Waxy to vitreous when wet

Identified July 15, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater in cavities of other rocks or as a replacement mineral. The yellow and orange hues are caused by iron oxides (limonite/hematite) leaching into the microcrystalline quartz structure over millions of years.

Uses & applications

Commonly used for lapidary work (tumbled stones, cabochons), decorative landscaping, and as a collectible for rockhounds due to its potential for internal patterns.

Geological facts

This specimen appears to be a water-worn river cobble. The presence of 'pitted' areas and smooth surfaces suggests it has been transported by water. Iron staining is one of the most common ways natural quartz takes on bright autumnal colors.

Field identification & locations

Identify in the field by its translucency (when held to light), waxy feel, and inability to be scratched by a steel knife. Common in riverbeds, gravel pits, and glacial till throughout North America.