Jasper stands as one of the most diverse and historically significant gemstones in the mineral kingdom. As an opaque variety of cryptocrystalline silica, specifically a form of chalcedony, it has captivated humanity for millennia with its earthy palette and intricate patterns. While often associated with a specific birth month, its true value lies in the sheer variety of materials that fall under its broad classification. This article delves into the gemological nature of jasper, its many forms, the myths surrounding misidentified stones, and the practical considerations for collectors and jewelers, drawing exclusively from the provided sources.
The term "jasper" is frequently used in trade to describe nearly any colorful, silica-rich stone, a practice that can lead to confusion among purists and enthusiasts alike. Authentic jasper is a cryptocrystalline intermixture of microscopic quartz and its polymorph, moganite, appearing as a smooth, waxy stone to the naked eye. Its hardness, generally rated at 7.0 on the Mohs scale, makes it suitable for a wide range of jewelry applications, from rings to bracelets. However, not all jaspers are created equal; some are more coarse, while fine-grained varieties rival the smoothness of translucent chalcedony.
The journey to understanding jasper involves navigating a landscape of trade names, geological formations, and even stones that are not jasper at all. From the banding of jaspilite to the orbs of ocean jasper, each variety tells a unique story of formation and location. This exploration will separate fact from folklore, providing a clear, expert perspective on this beloved stone.
The Nature of Jasper: Definition and Gemological Properties
At its core, jasper is a form of cryptocrystalline silica. The provided sources define it specifically as an opaque variety of chalcedony. Chalcedony itself is a complex intermixture of microscopic crystals of quartz and its polymorph, moganite, combined at such a small scale that it requires a thin slice and a microscope to discern. To the unaided eye, it presents as a smooth, waxy stone.
The remarkable variety in jasper's appearance stems from the various impurities within the stone. These inclusions are responsible for the vast spectrum of colors and patterns, meaning that no two nodules are exactly alike. This inherent uniqueness is a primary reason for its enduring popularity among stone collectors.
A key gemological property for any gemstone intended for jewelry is its hardness. Jasper generally has a hardness of 7.0 on the Mohs scale. This level of hardness makes it suitable for various jewelry types, including rings and bracelets, which is not the case for all gemstones. However, the sources note that not all jaspers are equal in their workability. Some are more coarse, which can make them rougher to work with for lapidaries, while "fine" jaspers are as hard and smooth as any form of translucent chalcedony.
A World of Variety: Common Types of Jasper
The classification of jasper is vast, with hundreds of different varieties existing, largely dependent on the locale of their discovery. The following are some of the most common and notable types as described in the sources.
Brecciated Jasper This variety is characterized by a distinct formation process. The general idea is that the stone was cracked during tectonic activity before being re-formed and cemented under the earth. Often, these jaspers appear to be cemented together with clear chalcedony, which gives them a distinctive look. The majority of brecciated jasper material is red and yellow, though nodules containing blue, green, or white jasper can be found. Unlike most jaspers, brecciated jasper often exhibits a three-dimensional effect after being polished properly, as the chalcedony cement allows one to see a few millimeters into the stone.
Jasp-Agate (Agate Jasper) Jasp-agate is a formation where jasper is interspersed with agate. In gemological terms, agate generally refers to any transparent variety of chalcedony that has extensive inclusions. Stones of this type will have sections that allow light to pass through once slabbed. These are distinct from heavily included agates, such as plume agate, due to the fact that the jasper is a distinct stone and not simply crystalline metallic salts contained within the agate. Jasp-agates are often brecciated as well. They are an uncommon find in most places that have both jasper and agate present, but are particularly common in certain regions of the Mojave desert in Southern California and Arizona. Each jasp-agate is a unique treasure.
Mookaite Mookaite refers to a polychromatic, or multi-colored, jasper found in Australia. Its vibrant and varied color palette makes it a distinctive and sought-after variety.
Kaleidoscope Jasper Found only in a family-run mine in Oregon, Kaleidoscope jasper is a unique form that often bears brilliant colors in broad bands. These colors are typically much brighter than those found in most jaspers, and some exhibit a wooden pattern. It appears to be a form of fossilized wood for the most part, with the petrified wood giving many of the distinctive patterns found within the material. Some of this material even possesses a schiller optical effect. Due to its single-location origin and unique characteristics, Kaleidoscope jasper can be quite expensive. For lapidaries, however, it is often worth the price, as the end result of cabbing and polishing this material is considered second-to-none in the world of jaspers.
Jaspilite (Tiger Iron) Jaspilite is the name used for stones cut from banded ironstone formations. These are complex formations consisting of alternating layers of blood-red hematite and low-iron chert or jasper, generally appearing as alternating stripes of red and grey or black material. The trade name "tiger iron" is commonly used when this stone is cut as a gemstone. While jasper is contained in the formation, there may also be metamorphic stones such as quartzite within it. Banded iron formations are fairly rich in iron but are considered very low-grade ore in most cases. Consequently, the majority of this material is removed to be cut for decorative objects or gemstones for jewelry.
Orbicular Jasper This type of jasper contains many little orbs of differing colors. The majority of this material comes from Madagascar and is generally sold under the trade name "Ocean Jasper." It is often green in color, but red, white, and yellow stones also exist. The spheres that make up the "orbs" in a cut stone appear to be either quartz or feldspar. The hypothesis behind their formation relates to rapid formation around the nucleus of crystalline materials.
The "Not-Quite Jaspers": A Critical Look at Trade Names
A significant portion of the provided material is dedicated to stones that are commonly called "jasper" but are, in fact, not jasper at all. This highlights a common issue in the gem trade where the term is used loosely for any colorful, silica-rich stone. Understanding these distinctions is crucial for accurate identification and appreciation.
Dalmatian Jasper Dalmatian "jasper" is a black and white spotted rock found in one region of Mexico. It is not a jasper, nor is it even a rhyolite. Instead, Dalmatian jasper is comprised of albite (a plagioclase feldspar mineral) and quartz in the white sections. The black portions of the stone, commonly assumed to be schorl, are actually a rare mineral called arfvedsonite. While definitely not a jasper, it still possesses a certain aesthetic appeal.
Rainforest Jasper This stone is commonly sold online and is generally seen in red or green forms with a brecciated pattern dotted with orbs similar to other orbicular jaspers. However, it is not a jasper; it is a rhyolite with a coarser structure than true jasper. The majority of this material is exceptionally fine-grained for a rhyolite, and there is no shame in cutting it into cabochons and carvings. This also means the material can be found in rather large pieces suitable for larger works like carvings and small statues.
Bumblebee Jasper Perhaps the most egregious offender in this category is Bumblebee Jasper. It is not a rhyolite, not a jasper, not quartz, and not quartzite. In fact, it contains no silica minerals at all. Instead, it is a complex mixture of calcite, pyrite, hematite, and realgar. The crystalline structure of the calcite is interesting but is not remotely related to silica minerals. Precautions must be taken when cutting this stone due to the presence of realgar, an arsenic-containing mineral. While an N95 or better respirator is already recommended for cutting stone, wearing gloves is also a good idea. Once cut and polished, however, the material is safe to handle as long as it is not chewed on.
Crocodile Jasper Common knowledge holds that crocodile jasper is both a jasper and a fossil known as a stromatolite. Further studies have shown this not to be the case. Instead, this stone is rhyolite formed from quartz, potassium feldspar, albite, and aegirine. The "stromatolites" that people long assumed formed the "eyes" on this stone are actually needles of amphibole minerals. It remains a beautiful stone and is exceptionally fine-grained for a rhyolite.
Geological Formation and Mining Locations
The sources provide information on the formation and locations of specific jasper varieties, painting a picture of a globally distributed gemstone with localized hotspots.
Formation Processes Jasper forms through processes that involve silica-rich solutions. For instance, brecciated jasper forms when a stone is cracked during tectonic activity and later re-formed and cemented under the earth, often with clear chalcedony acting as the cement. The formation of orbicular jasper, like Ocean Jasper, is hypothesized to involve rapid formation around a nucleus of crystalline materials. Jaspilite (tiger iron) originates from banded ironstone formations, which are complex layers of hematite and chert or jasper.
Mining Locations The provided sources mention several specific locations for various jasper types: - Dalmatian Jasper: Found in one region of Mexico. - Jasp-Agate: Particularly common in certain regions of the Mojave desert in Southern California and Arizona. - Kaleidoscope Jasper: Exclusively found in a family-run mine in Oregon. - Ocean Jasper (Orbicular Jasper): The majority of this material hails from Madagascar. - Morgan Hill Jasper: The most popular variety comes from the area around Morgan Hill, California, where it is increasingly rare but in high demand. - Mookaite Jasper: Found in Australia.
The sources also note that jasper is a common find across the planet and can be found in several areas in the United States for those looking to collect a sample.
Symbolism and Historical Context
While the sources do not provide extensive historical lore or metaphysical beliefs specific to jasper as a birthstone, they do touch on its cultural and trade significance. The long-standing use of the term "jasper" for a wide variety of colorful stones indicates its deep-rooted place in human culture, even if the precise mineralogical identity has been debated.
The practice of naming stones after animals or natural patterns, such as Dalmatian, Crocodile, and Bumblebee Jasper, reflects a human tendency to find symbolism and connection in the natural world. These trade names, while not always scientifically accurate, have created a rich tapestry of variety that appeals to collectors and enthusiasts. The fact that Kaleidoscope Jasper is found in a single family-run mine in Oregon and is considered unique enough to command a high price speaks to the value placed on rarity and distinctive appearance.
Care and Cleaning for Jasper Jewelry
Given its gemological properties, jasper requires specific care to maintain its beauty. The primary characteristic to consider is its hardness, which is generally 7.0 on the Mohs scale. This makes it relatively durable and suitable for everyday jewelry, but it is not impervious to damage.
For stones like Bumblebee Jasper, which contain realgar, special precautions are necessary during the cutting and polishing process due to the arsenic content. Once the stone is cut and polished, it is safe to handle, but the initial work requires safety equipment like an N95 respirator and gloves.
For general cleaning, the waxy surface of jasper can be washed with warm, soapy water and a soft brush. Ultrasonic cleaners are generally safe for most jaspers, but steam cleaning should be avoided, as sudden temperature changes can potentially damage the stone, especially if it has any fractures or inclusions. Storing jasper jewelry separately from harder stones will prevent scratching, as stones with a higher Mohs hardness can abrade the jasper's surface.
Conclusion
Jasper, as an opaque variety of chalcedony, represents a fascinating intersection of geology, trade, and artistry. Its defining characteristic—cryptocrystalline silica with myriad impurities—results in an almost limitless array of colors and patterns, from the banded stripes of jaspilite to the concentric orbs of Ocean Jasper. The provided sources clarify that while the term "jasper" is often used broadly, true jasper is a specific type of silica mineral, and many stones bearing the name are actually different materials like rhyolite or calcite-based mixtures.
The diversity of jasper, from the rare and unique Kaleidoscope Jasper of Oregon to the globally distributed common varieties, ensures its continued appeal to collectors and jewelers. Its hardness of approximately 7.0 on the Mohs scale makes it a practical choice for jewelry, though care must be taken with specific varieties that may contain hazardous minerals. Ultimately, jasper's value lies in its earthy beauty, its historical significance as a collected stone, and the unique story each piece tells through its inclusions and patterns.