sedimentary
Yellow Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs); Color: Yellow to brownish-yellow; Luster: Vitreous to waxy; Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91
- Hardness
- 6
- Color
- Yellow to brownish-yellow
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Yellow to brownish-yellow; Luster: Vitreous to waxy; Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91
Formation & geological history
Formed through the deposition of silica from water-rich solutions into volcanic ash or sedimentary rocks. The yellow coloration is caused by the presence of goethite or other iron hydroxide minerals. It can form in any age range from Precambrian to recent.
Uses & applications
Primarily used for lapidary work, jewelry (cabochons and beads), ornamental carvings, and as a collector's specimen. It is also historically used for physical and spiritual protection in various cultures.
Geological facts
Jasper is an opaque variety of chalcedony. Yellow jasper specifically was historically revered by ancient civilizations as a stone of endurance and perseverance. Some specimens are so dense they can take a mirror-like polish.
Field identification & locations
Identify in the field by its waxy appearance, extreme hardness (it will scratch glass), and its lack of transparency even on thin edges. It is commonly found in desert regions, riverbeds, and volcanic outflows throughout the American West and Madagascar.
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