sedimentary
Jasper in Quartz (River Cobble)
Silicon Dioxide (SiO2) with Ferric Iron inclusions
Hardness: 6.5-7 (Mohs scale); Color: Cream/gray quartz with reddish-brown jasper patches; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None/Conchoidal fracture; Specific gravity: 2.6-2.7
- Hardness
- 6
- Color
- Cream/gray quartz with reddish-brown jasper patches
- Luster
- Dull 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 scale); Color: Cream/gray quartz with reddish-brown jasper patches; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None/Conchoidal fracture; Specific gravity: 2.6-2.7
Formation & geological history
Formed through the deposition of silica-rich fluids in volcanic or sedimentary voids. This specific specimen is a water-worn river cobble, rounded by alluvial transport over thousands of years.
Uses & applications
Commonly used for lapidary work (tumbling, cabochons), landscaping, and as a educational specimen for beginner collectors.
Geological facts
Jasper gets its red color from iron impurities. When found in riverbeds like this, the smooth exterior is created by 'natural milling' where the rock is polished by sand and water over long distances.
Field identification & locations
Identify by its hardness (it will scratch glass) and the characteristic 'skin' or cortex that forms on river rocks. Look for these in gravel bars or dry creek beds in volcanic regions.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone (Quartz-rich)
Arenite (SiO2)
sedimentary
Sandstone (with man-made markings)
Arenite (composed primarily of Quartz, SiO2)
sedimentary