sedimentary
Brown Quartz (Jasper or Chert)
Silicon Dioxide (SiO2)
Hardness: 6.5-7 Mohs. Color: Brown, tan, or reddish-brown. Luster: Vitreous to waxy. Crystal Structure: Hexagonal/Microcrystalline. Cleavage: None (conchoidal fracture). Specific Gravity: 2.6-2.7.
- Hardness
- 6
- Color
- Brown, tan, or reddish-brown
- 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: Brown, tan, or reddish-brown. Luster: Vitreous to waxy. Crystal Structure: Hexagonal/Microcrystalline. Cleavage: None (conchoidal fracture). Specific Gravity: 2.6-2.7.
Formation & geological history
Forms primarily through the accumulation of microcrystalline silica in marine or freshwater environments. Often found as nodules in limestone or as replacement material in fossils.
Uses & applications
Used primarily in lapidary work for making cabochons, beads, and tumbled stones. Historically used for making tools and arrowheads due to its sharp fracture edges.
Geological facts
This specimen appears to be a common microcrystalline variety of quartz. Quartz is the second most abundant mineral in Earth's continental crust and is incredibly resistant to chemical weathering.
Field identification & locations
Identify in the field by its hardness (it should scratch glass), its smooth conchoidal fracture, and lack of visible crystal grains. Commonly found in riverbeds, gravel pits, and sedimentary outcrops.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Sandstone
Arenite
sedimentary