Yellow Jasper
Quartz var. Jasper (Yellow variety) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal (Crystalline system), though appearing massive or microcrystalline (cryptocrystalline). Typically occurs in massive or nodular habits without visible crystals.
Mineral Group
Silicates (Tectosilicates subgroup; member of the Chalcedony/Quartz group).
Chemical Formula
SiO2 (Silicon Dioxide) with Goethite or Iron Oxide (Fe2O3) inclusions providing the yellow to ochre pigmentation.
Formation Process
Sedimentary or Hydrothermal. Formed from the infiltration of silica-rich fluids into volcanic ash or sedimentary rocks, where the silica replaces the original material or fills cavities (petrifaction/replacement).
About This Crystal
An opaque, microcrystalline variety of quartz. It features a dull to earthy luster in its raw state (as pictured), turning vitreous when polished. The color is a characteristic mustard yellow to tan-brown with a smooth, fine-grained texture and no visible cleavage planes.
Physical Characteristics
Color: Mustard yellow to brownish-yellow; Streak: White; Cleavage: None; Fracture: Conchoidal (shell-like) to uneven; Specific Gravity: 2.58–2.91; Tenacity: Brittle; Fluorescence: Generally inert (none).
Optical Properties
Refractive Index: 1.544–1.553; Birefringence: None (as it is an aggregate); Pleochroism: None; Dispersion: Low; Optical Character: Aggregate. The material is completely opaque.
Hardness & Durability
Origin Region
Found globally; notable sources include South Africa, India, Brazil, Madagascar, and the United States (specifically Utah and Oregon). Often found in sedimentary or volcanic environments.
Hardness & Durability
Mohs Hardness: 6.5–7. Excellent durability and toughness due to its cryptocrystalline structure, making it highly resistant to scratching and suitable for daily wear in jewelry.
Care & Maintenance
Clean with warm soapy water and a soft brush. While stable, it should be kept away from harsh chemicals like hydrofluoric acid. Can withstand ultrasonic cleaners, but mechanical cleaning is safer for raw specimens.
Rarity & Value
Common. Value is generally low to moderate, determined by the vibrancy of the yellow hue and the presence of interesting patterns. Raw chunks are very affordable, often used as lapidary rough or landscape stone.
Special Characteristics
Exhibits a very fine-grained texture that allows for a high polish. Does not show phenomena like chatoyancy, but can occasionally feature 'dendritic' inclusions or color banding.
Lore & History
Historically used as a 'stone of protection' by ancient civilizations and travelers. In traditional lore, it is associated with the Solar Plexus chakra and believed to promote self-confidence, mental clarity, and physical stamina.