Jasper is an opaque form of microcrystalline quartz packed with other minerals, mostly iron oxides and clay. The impurities can make up a large part of the stone, and they give jasper its strong colors and patterns: reds, yellows, browns and greens, often in scenic patterns, orbs or swirls. Jasper takes a fine polish and is tough, so carvers have used it for seals, vessels and inlay for thousands of years. Many jasper names are trade names for local material, and some stones sold as jasper are not jasper at all.
What jasper is
Jasper belongs to the same broad family as chalcedony and agate: quartz made of crystals too small to see. Mineralogists sometimes separate jasper from chalcedony by texture, describing jasper as grainy and chalcedony as fibrous. In the trade, the simplest rule is translucency. Chalcedony and agate let light through. Jasper is opaque. The page on diaphaneity explains these terms.
Jasper's color comes from the material mixed into the silica:
- Hematite gives red.
- Goethite and limonite give yellow and brown.
- Chlorite, actinolite and other green minerals give green.
- Manganese oxides and carbon give black.
Jasper forms in many settings. It can replace volcanic ash, fill cracks in rock, form around hot springs, or develop from silica-rich sediments. Banded iron formations, very old rocks made of alternating layers of iron oxide and silica, contain bands of red jasper. Our page on sedimentary rocks and gemstones covers related processes.
Types of jasper
Dealers sell hundreds of named jaspers. Many names refer to one deposit and can change as mines open and close. These are some of the best-known.
Red jasper
Red jasper is the classic form, colored by hematite. It ranges from brick red to deep blood red and is often even in color, sometimes with darker veins. India, Brazil, Madagascar and the United States are common sources.
Yellow jasper
Yellow jasper owes its mustard to tan color to iron hydroxides such as goethite. Heating can turn yellow jasper red by converting goethite to hematite.
Picture jasper
Picture jasper has patterns that look like scenery, with layers that suggest hills, sky and water. The layers formed as silica-rich sediments or mud settled and were later stained by iron. Oregon and Idaho in the United States are known for picture jaspers such as Biggs and Owyhee jasper. Cutters orient slabs to frame a scene, much as a photographer frames a view.
Ocean jasper
Ocean jasper, also called orbicular jasper, comes from the northwest coast of Madagascar. It shows round, eye-like orbs in green, pink, white, yellow and red, often with sparkling druzy quartz in cavities. Some of the deposits are reachable only at low tide. The orbs are thought to have grown outward from many centers at once as silica crystallized in volcanic rock.
Kambaba jasper
Kambaba jasper is dark green with black round patterns. It comes from southern Africa, especially South Africa and Madagascar. Despite the name, it is usually considered a stromatolite rock: fossilized layers made by ancient microbial mats, replaced and mixed with silica. Because it can contain a good deal of non-quartz material, it may be softer than true jasper.
Polychrome jasper
Polychrome jasper, also sold as desert jasper, was found in Madagascar in the 2000s. It shows bold swirls and bands of red, orange, cream, green and purple. Its colors and patterns make it a favorite for cabochons and spheres.
Other names
Bloodstone, dark green with red spots, is sometimes classed as jasper and sometimes as chalcedony. Mookaite from Western Australia is a colorful red, yellow and purple silicified rock. Many trade names, such as "dalmatian jasper" or "zebra jasper," are applied to rocks that are not jasper in a mineral sense. Take dalmatian "jasper": it is an igneous rock with black spots of other minerals.
Jasper in history and carving
Jasper has a long record in carving and adornment. Egyptians carved red jasper into amulets and inlays, and Mesopotamian craftworkers cut it into cylinder seals. The page on Mesopotamian jewelry describes those seals. Greek and Roman engravers used red and green jasper for intaglios.
Its toughness and lack of cleavage make jasper a good stone for larger objects. Renaissance hardstone carvers in Italy made vessels and inlays from it, and Florentine pietra dura panels used jasper among many other colored stones to create pictures. Our page on Renaissance gem cutters covers that tradition. Russian workshops carved jasper from the Urals into large vases and table tops.
Today jasper is cut as cabochons, beads, spheres, carvings, tumbled stones and decorative objects.
Treatments and imitations
Most jasper is untreated. Some is dyed, especially to create blues or brighter colors that do not occur naturally. Howlite and magnesite, two white minerals, are often dyed to imitate jasper or turquoise. Some red "jasper" in cheap beads is dyed quartzite or even reconstituted material. The page on gemstone treatments covers dyeing and how to spot it.
Buying jasper
Judge jasper on pattern, color and polish. A strong, attractive pattern, crisp boundaries between colors and a smooth, glassy finish without pits all add value. For picture jasper, a balanced scene matters. For ocean jasper, clean orbs with contrast and druzy pockets are the most popular. Since many trade names overlap, ask what the material is and where it comes from.
Durability and care
True jasper is about 6.5 to 7 on the Mohs scale, has no cleavage and is tough. It wears well in rings and bracelets. Stones with a lot of clay or other minerals can be softer and take a duller polish. Clean jasper with warm soapy water and a soft brush. Avoid harsh chemicals, especially on dyed material.
Frequently asked questions
Is jasper a type of quartz?
Yes. Jasper is opaque microcrystalline quartz with a large share of other minerals, mainly iron oxides and clay, which give it color.
What is the difference between jasper and agate?
Agate is translucent and usually banded. Jasper is opaque and colored by impurities. Both are microcrystalline quartz.
Where does ocean jasper come from?
Ocean jasper comes from coastal deposits in northwest Madagascar. Some of the outcrops are reachable only at low tide.
Is all "jasper" real jasper?
No. Names like dalmatian jasper and zebra jasper are trade names for rocks that are not jasper in the mineral sense. Ask what a stone actually is.