Short answer: "jasper" on a label guarantees very little. True jasper is opaque chalcedony (SiO2, Mohs 6.5 to 7), and many locality and pattern names such as Morrisonite, Biggs or Stone Canyon jasper describe exactly that. Others, such as dalmatian "jasper" and African "turquoise", are rocks borrowing a name, and brightly colored names such as sea sediment or impression jasper often cover dyed or resin-bonded material. A steel blade, a loupe and a cotton swab sort most of them out.
Why is "jasper" such a loose name?
Because it was never a strict scientific term. Geology.com puts it directly: the name "jasper" is more of a gemological term than the name of a material used by geologists (Geology.com). The same hand specimen might be called chert by one person, flint by another and jasper by a third. Lapidaries choose "jasper" for the best-looking opaque microcrystalline quartz, the material that cuts accurately, takes a bright polish and shows strong color and pattern.
That looseness is an open door for trade names. Once a buyer has learned that jasper is an attractive, durable, inexpensive stone, any patterned rock sells better with "jasper" attached. Some of those names are accurate, some stretch the word, and a few hide a treatment.
What does real jasper look like on paper?
Minerals.net describes jasper as an opaque variety of chalcedony, with a hardness of 6.5 to 7, a refractive index of 1.54 to 1.55 and a specific gravity of 2.63 to 2.65 (Minerals.net). The International Gem Society explains the naming logic within the cryptocrystalline quartz family: the solid-colored materials, mostly chalcedony stained by oxides, are referred to as jaspers, while banded or moss-included varieties are called agate (International Gem Society).
Those numbers are the benchmark for every test below. Anything sold as jasper that scratches with a steel knife, feels light, or lets light through thin edges is either not jasper or not only jasper.
Geology.com also gives a field method using a fresh conchoidal fracture surface. A vitreous luster on the break means coarsely crystalline quartz; a dull luster means a variety of chalcedony; and an opaque piece with that dull break is jasper.
Which jasper trade names describe real jasper?
Most locality names are honest. They tell you where the material came from and, to an experienced eye, what it should look like. Minerals.net lists dozens; these are some of the more useful to know because they show how specific a good name can be.
| Trade name | What Minerals.net says it is |
|---|---|
| Morrisonite | Multicolored jasper from the Owyhee River gorge, Malheur County, Oregon |
| Wascoite | Jasper from Wasco County, Oregon, with irregular yellow, pink and red concentric bands |
| Rogueite | Green jasper from the Rogue River in Oregon |
| Stone Canyon jasper | Yellowish brecciated jasper from Stone Canyon, near San Miguel, California |
| Cave Creek jasper | Reddish jasper from near Cave Creek, Maricopa County, Arizona |
| Egyptian jasper | Orbicular jasper with white and gray circles on red, found as beach pebbles in Egypt |
| Kinradite | Orbicular jasper with concentric rings of colorless or white quartz |
| Jaspilite | Banded rock that is a mixture of hematite and jasper |
Pattern names can be honest too. Zebra jasper is described as dark brown jasper with lighter brown to white banding streaks; leopard jasper as orbicular jasper with tan rings; opal jasper as brecciated jasper cemented by opal; moss jasper as jasper or chalcedony with dense inclusions of green hornblende. Minerals.net even flags a regional overlap: a similar jasper from the beaches of Washington state is sometimes also sold as Egyptian jasper. So a locality name is a claim, not a certificate.
Which "jaspers" are not jasper at all?
These names attach "jasper" or another stone's name to a material that is a different rock, or that has been altered. Our main jasper guide covers three famous examples already; the ones below are the names buyers ask about most at a counter.
Dalmatian stone
The white stone with black spots sold as dalmatian jasper is a speckled crystalline rock, not opaque chalcedony; under a loupe it shows separate grains of different minerals rather than the even, dense body of jasper. It is also one of the stones commonly dyed for the tumbled-stone trade: Geology.com's photo of dyed tumbled stones includes dalmatian stone alongside agate, howlite, granite and feldspar (Geology.com). Natural dalmatian stone is cream to white with black spots; pink, blue or green versions are dyed.
African turquoise
There is no turquoise in it. Turquoise is a hydrous copper aluminum phosphate, CuAl6(PO4)4(OH)8·4H2O, with a hardness of 5 to 6 (Minerals.net). "African turquoise" is a trade name for a mottled green to blue-green rock, usually described in the trade as a jasper, whose color is often deepened by dye. Under the FTC Guides, using a gem name such as turquoise for a product that is not that mined stone, without qualification, is unfair or deceptive, which is why careful sellers write African "turquoise" in quotes or call it African jade-jasper.
Sea sediment jasper and impression jasper
Neither name identifies a mineral or a rock. Both are applied to brightly colored, strongly veined material: vivid greens, blues, reds and purples crossed by a net of dark or gold lines. Pieces sold under these names are frequently dyed, and some are reconstituted, meaning crushed stone bonded back together with resin and colored. The name tells you nothing about which you have, so treat every piece as unknown until it passes the checks below.
Porous stones dyed to imitate
The wider pattern behind these names is dye in porous material. Minerals.net notes that most jasper is natural and untreated, though occasionally it is dyed. Softer, more porous stones take dye far more readily: the International Gem Society describes how magnesite accepts dye treatments very well because of its porosity, and how dyed pieces are sometimes sold as turquoise (International Gem Society). When a bright "jasper" is soft, that is the likeliest explanation.
How to check a stone sold as jasper, step by step
- Steel test. On an unseen spot, try to scratch it with a steel knife or nail. Jasper, at 6.5 to 7, resists. A mark means a softer rock or a resin composite.
- Opacity check. Shine a flashlight through a thin edge. Jasper stays opaque. Translucence suggests agate or chalcedony; a glassy, even glow suggests resin.
- Loupe the cracks and veins. Dye collects in fractures, pits and drill holes, leaving color darker along lines than in the body. Natural veining has its own mineral texture.
- Swab test. A cotton swab with acetone or nail polish remover, rubbed on a hidden spot, picks up color from many dyed stones. Geology.com warns that water-soluble dyes can even transfer onto hands and clothes.
- Look for resin signs. Reconstituted pieces show angular chips floating in a uniform matrix, tiny gas bubbles, a plasticky warmth in the hand and a slightly low weight.
- Fade check. Dyed stones are often not colorfast; Geology.com notes that some lose their color with prolonged exposure to sunlight and usually fade outdoors.
- Price sanity. Neon colors at bargain prices per pound point to dyed material; natural, named-locality jasper is priced on pattern and polish.
Our planned guides to dyed stones and stabilized and reconstituted stones go deeper on each treatment.
Grading terms you will see on jasper listings
- Natural: no dye or coating. It does not rule out wax or oil on the polish, which Geology.com notes some producers use to hide fractures or poor polishing.
- Stabilized: impregnated with resin to harden a porous or crumbly stone.
- Reconstituted: crushed material bonded with resin. Should always be stated.
- Dyed or color enhanced: artificial color added. Acceptable when disclosed.
- Locality name: a claim about origin; ask for a deposit or region, not just a country.
What to look for when you buy jasper under a trade name
Ask the seller for the rock name, the locality and any treatment, and buy on pattern contrast, polish quality and freedom from pits and chips. Opaque, hard, naturally colored stone is the goal. These pieces from our stock illustrate the honest end of the market.
- Polychrome Jasper Crystal Freeform Desert Jasper Stone: banded terracotta, cream and burgundy from Madagascar; the earthy, uneven tones are what natural iron-colored jasper looks like.
- Brecciated Jasper: angular red fragments naturally cemented together; compare the natural, mineral-filled seams with the uniform resin of reconstituted stone.
- Pink Zebra Jasper 2.37lbs 1 Pair: a matched pair of towers from Madagascar with dusty rose and cream banding; check that both towers share the same soft, natural palette.
- Dalmation Jasper Tumble: the classic cream-and-black spotted stone; a cheap piece to practice the loupe test and see the granular rock texture.
- Ocean Jasper Crystal Carved Heart Madagascar: orbicular jasper with green, cream and pink orbs; true orbicular pattern runs through the stone rather than sitting on the surface.
- Kambaba (Crocodile) Jasper Polished Sphere Sculpture: a 75 mm sphere from Madagascar sold under two trade names at once; a good example of asking what the rock is made of before buying on the name.
Digital Towns Market
Jasper in stock
Frequently asked questions
Is sea sediment jasper real jasper?
Not reliably. "Sea sediment jasper" is a trade name, not a mineral or rock name, and pieces sold under it are frequently dyed and sometimes resin-bonded. Check hardness with steel, look for dye concentrated in cracks, and ask the seller whether it is natural, stabilized or reconstituted.
Is African turquoise real turquoise?
No. It contains no turquoise, which is a copper aluminum phosphate. African turquoise is a mottled green to blue-green rock usually described in the trade as jasper, often with dye-enhanced color. It is an attractive, inexpensive stone, but it should not be sold as turquoise.
What is impression jasper?
Impression jasper is a selling name for brightly colored, veined material rather than a defined stone. It does not identify a mineral or a locality. Treat any piece as possibly dyed or reconstituted until a swab test, a loupe check for resin and a hardness test say otherwise.
Is dalmatian jasper a jasper?
No. Dalmatian stone is a speckled crystalline rock rather than opaque chalcedony. Under a loupe you can see separate mineral grains. Its natural colors are cream to white with black spots; brightly colored versions are dyed.
How can you tell if jasper is dyed?
Look for color concentrated along cracks and pits, colors brighter than any natural iron or manganese tone, and color that rubs off on an acetone swab. Most true jasper is natural and untreated, so neon shades are a strong hint of dye or of a different material.
Sources
- Geology.com, Flint, Chert, and Jasper: https://geology.com/rocks/flint-chert-jasper/
- Minerals.net, The gemstone jasper: https://www.minerals.net/gemstone/jasper_gemstone.aspx
- International Gem Society, Quartz Value, Price, and Jewelry Information: https://www.gemsociety.org/article/quartz-jewelry-and-gemstone-information/
- Geology.com, Tumbled Stones: https://geology.com/rock-tumblers/tumbled-stones/
- Minerals.net, The gemstone turquoise: https://www.minerals.net/gemstone/turquoise_gemstone.aspx
- International Gem Society, Magnesite Value, Price, and Jewelry Information: https://www.gemsociety.org/article/magnesite-jewelry-and-gemstone-information/
- eCFR, 16 CFR Part 23, Guides for the Jewelry, Precious Metals, and Pewter Industries: https://www.ecfr.gov/current/title-16/chapter-I/subchapter-B/part-23