sedimentary
Red Jasper or Carnelian (Agate)
Silicon Dioxide (SiO2)
Hardness: 6.5-7 Mohs; Color: Deep reddish-brown; Luster: Vitreous to waxy; Crystal structure: Hexagonal (Microcrystalline/Cryptocrystalline); Conchoidal fracture.
- Hardness
- 6
- Color
- Deep reddish-brown
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 Mohs; Color: Deep reddish-brown; Luster: Vitreous to waxy; Crystal structure: Hexagonal (Microcrystalline/Cryptocrystalline); Conchoidal fracture.
Formation & geological history
Formed through the accumulation of silica in groundwater within volcanic rock cavities or sedimentary layers. The reddish color is due to iron oxide (hematite) inclusions. Java, Indonesia, is rich in volcanic deposits that produce high-quality chalcedony and jasper.
Uses & applications
Commonly used as a gemstone (cabochons), in lapidary art, for jewelry making, and as a popular collector's item due to its polish and color.
Geological facts
In Indonesia, such stones are often referred to as 'Batu Akik'. Historically, red jasper was known as the 'warrior's stone' and was believed to provide protection and physical strength.
Field identification & locations
Identify by its hardness (cannot be scratched by a steel knife), smooth waxy feel when polished, and opacity or slight translucency at the edges. Very common in riverbeds across West and Central Java.
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