Jasper
Silicon dioxide (SiO2), opaque microcrystalline quartz
An opaque, often colorfully patterned variety of chalcedony quartz, popular for tumbling, carving, and jewelry.
- Mohs hardness
- 6.5-7
- Color
- Red, brown, yellow, green, and multicolored patterns
- Type
- mineral
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Overview
Jasper is an opaque variety of microcrystalline quartz (chalcedony) that owes its color and patterns to mineral impurities such as iron oxides and clay, plus included grains and organic matter. It commonly appears in earthy reds, browns, yellows, and greens, frequently banded, spotted, or scenic.
Unlike translucent agate, jasper is opaque, and the two often occur together. The name covers a huge range of named patterns and localities, from picture jasper to ocean jasper.
With a hardness of about 6.5-7 and excellent toughness, jasper takes a high polish and has been used ornamentally since antiquity.
Formation & geology
Jasper forms when silica-rich fluids precipitate into sediment, volcanic ash, or fractures, cementing fine particles and impurities into a dense, opaque mass of microscopic quartz. Iron and other oxides trapped during this process create the characteristic colors and patterns.
It occurs worldwide in sedimentary and volcanic settings and as nodules, veins, and replacement deposits. Notable sources include the United States (Oregon, Idaho, Arizona), India, Madagascar, Russia, and Australia. Many trade names reflect specific deposits, such as Mookaite from Australia and Bruneau jasper from Idaho.
How to identify it
Jasper is opaque (light does not pass through even thin edges), with a hardness of 6.5-7 and a dull to waxy luster that brightens to vitreous when polished. It has a white streak and conchoidal fracture, and often shows distinct color banding, spots, or scenic patterns.
Key look-alikes are agate (translucent, banded), chert and flint (duller, usually gray to black), and some opaque chalcedony. The reliable test is opacity plus quartz hardness: jasper will scratch glass and steel, and unlike marble or calcite it does not react with acid.
Uses & significance
Jasper is a popular lapidary and ornamental stone, cut into cabochons, beads, tumbled stones, bookends, and carvings. Its toughness and high polish make it durable for jewelry and décor, and it has been used for seals and mosaics since ancient times.
Many collectors seek specific patterned varieties prized for their scenic or picturesque appearance. Metaphysically, jasper is called the "supreme nurturer," associated with grounding, stability, and endurance, with red jasper linked to vitality and green to balance. It has limited industrial use beyond ornamental and lapidary applications.
Frequently asked questions
What is the difference between jasper and agate?
Both are chalcedony quartz, but jasper is opaque and usually patterned with impurities, while agate is translucent and typically banded.
What gives jasper its colors?
Mineral impurities, mainly iron oxides plus clay and organic matter, produce reds, browns, yellows, greens, and the many patterns.
Is jasper a real gemstone?
Jasper is an opaque variety of quartz used as a semiprecious ornamental gem; it is durable and takes a fine polish.
How can I tell jasper from chert?
Jasper is usually brightly colored or patterned and polishes well, while chert is typically dull and gray to black, though both are microcrystalline quartz.
Jasper guides
In-depth guides for identifying, valuing, and understanding Jasper.
Jasper identified by the community
Real specimens identified with Rock Identifier.
