Jasper
Jasper is the broadest and most locality-dependent of the chalcedony varieties on this site: rather than one characteristic color or pattern the way carnelian means orange-red or agate means banding, jasper is defined mainly by what it isn’t — translucent. It is chalcedony carrying enough mineral impurities and fine inclusions to be fully opaque, and those same impurities are responsible for the huge range of colors and patterns different jasper localities produce, from solid brick red to swirling, landscape-like “picture jasper” prized for looking almost painted.
Species and variety. Jasper is a variety of chalcedony, the cryptocrystalline (fine-grained, fibrous) form of quartz, chemically SiO2 like agate, carnelian, and onyx. What separates it from those other varieties is opacity and impurity content rather than a different underlying mineral — the boundary between jasper and other opaque chalcedony varieties (bloodstone in particular) is genuinely not sharp in gemological practice, and some material is legitimately described either way.
Appearance and color range. Because its color comes from whatever mineral inclusions were present during formation at a given locality, jasper’s range is unusually wide even for a single gem variety: solid reds and browns, mottled multicolor patterns, and the distinctive banded or scenic patterns of picture jasper all fall under the same name. This locality-dependence means jasper is often marketed by where it’s from — a practice less common with more chemically uniform gems.
Hardness and everyday care. At roughly 6.5–7 on the Mohs scale, jasper wears well in everyday jewelry and carved objects, resisting scratches from ordinary use. It is commonly cut as cabochons or used in beadwork and carving rather than faceted, since its opacity gives faceting no optical benefit; mild soap and water is the safest cleaning method.
Where it is found. Jasper occurs widely, with notable material from India, Madagascar, Russia, the United States, and Australia — its broad geographic distribution is itself a byproduct of how commonly the conditions that form opaque, impure chalcedony occur in nature.
Birthstone role. Jasper appears in the historical (pre-20th-century) monthly list for March, alongside bloodstone. None of the three modern systems (US 1912, UK 2013, US current) retain it — all three give March to aquamarine and/or bloodstone instead, and jasper’s birthstone status today rests entirely on that older tradition.
Gemmological properties
| Mohs hardness | 6.5–7 |
|---|---|
| Crystal system | Trigonal (cryptocrystalline) |
| Chemical formula | SiO2 |
| Refractive index | 1.53–1.54 |
| Color family | Multicolour, Brown, Red |
| Variety of | chalcedony |
| Also known as | — |
| Origins | India, Madagascar, Russia, United States, Australia |
| Organic material | No |
Jasper is an opaque, impure form of chalcedony (microcrystalline quartz); its color and pattern vary widely by locality and the mineral inclusions present during formation.
Where Jasper appears as a birthstone
By month
| Month | System | Confidence |
|---|---|---|
| March | Historical (15th–20th century) | high |
Frequently asked questions
- What makes jasper different from other chalcedony varieties like agate or carnelian?
- Opacity and impurity, mainly. Jasper is chalcedony — cryptocrystalline quartz — that contains enough mineral impurities and inclusions to be fully opaque rather than translucent, and those impurities are also what give different jasper localities their very different colors and patterns, from solid red to complex multicolored "picture jasper" landscapes.
- Is bloodstone a type of jasper?
- It's classed both ways in different reputable sources — as a chalcedony variety in its own right, and as a variety of jasper because of its opacity and its formation alongside true jaspers. The boundary between "jasper" and other opaque chalcedony varieties isn't sharply defined in gemology, and bloodstone sits right on it.