sedimentary
Jasp-Agate
Cryptocrystalline Quartz (SiO2) with Iron Oxide inclusions
Hardness: 6.5-7 (Mohs); Color: Waxy grey-brown chalcedony with bright red jasper patches; Luster: Vitreous to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture).
- Hardness
- 6
- Color
- Waxy grey-brown chalcedony with bright red jasper patches
- Luster
- Vitreous to waxy
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 (Mohs); Color: Waxy grey-brown chalcedony with bright red jasper patches; Luster: Vitreous to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed when silica-rich fluids permeate volcanic or sedimentary rock cavities. The red 'jasper' is caused by iron impurities, while the translucent sections are chalcedony/agate. Often found in volcanic ash beds or gravel deposits.
Uses & applications
Commonly used for lapidary work, cabochons, jewelry, and as decorative pocket stones or healing crystals.
Geological facts
This specimen is a 'bridge' rock, containing both opaque Jasper and translucent Agate. The red color suggests hematite staining within the silica matrix. This material was historically used by indigenous peoples for stone tools due to its controlled fracturing.
Field identification & locations
Identify by looking for translucent edges (agate) mixed with opaque red areas (jasper). It will scratch glass easily. Commonly found in riverbeds or desert washes in the Western United States.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Sandstone
Arenite
sedimentary