sedimentary
Chert / Chalcedony Blend
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 (Mohs scale); Color: Variegated rusty orange, tan, and gray; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6
- Hardness
- 6
- Color
- Variegated rusty orange, tan, and gray
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Variegated rusty orange, tan, and gray; Luster: Waxy to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6
Formation & geological history
Formed through the accumulation of silica-rich fluids in sedimentary environments or as replacement of other minerals. Often found in nodules or bedded deposits within limestone or dolomite.
Uses & applications
Historically used for stone tools (knapping); currently used for lapidary work, decorative garden stones, and as a durable mineral specimen.
Geological facts
This specimen shows characteristic iron-oxide staining which gives it the reddish-orange hue. It belongs to the same family as jasper and agate.
Field identification & locations
Identify by its waxy luster, hardness (it will scratch glass), and conchoidal fracture (smooth, shell-like curves when broken). Commonly found in river beds or erosion zones near limestone formations.
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