Types of jasper rare8/24/2023 Poppy Jasper - One particularly colorful orbicular jasper is poppy jasper from near Morgan Hill, Santa Clara County, California, on the side of El Toro mountain. When you first see an orbicular jasper, regardless of its source, you have to wonder how such a lovely flower-like pattern forms in what appears to be a solid jasper rock. Orbicular Jasper VarietiesĪmong all the jaspers, the more popular type is orbicular jasper. With careful orientation and lapidary work, a Bruneau nodule will produce a large orbicular layering, bull’s eyes and lovely alternating domed tan to brown cabochons. The overall colors tend to be shades of brown to red, but are distinct enough to be very attractive.īruneau Jasper - Another jasper locality much better known for decades, Bruneau Canyon has become a major source of superb multi-hued brown jasper which formed in alternating light to dark brown layers of rounded nodules. The jasper from here was immediately named Picture jasper since it is not only linear but the multi-colored layers often appear like landscapes, horizons and village scenes. Picture Jasper - Years ago during some road work in Oregon, fine linear jasper was found in a place near Biggs Junction. The formation of these deposits dates back to one of the earliest times in earth’s history called the Great Oxygen Event that changed Earth’s atmosphere from poisonous clouds of methane, ammonia and carbon dioxide to nitrogen and oxygen. The name jasper is derived from the French word ‘jaspre’ which means spotted stone. These huge slabs are popular as decorative stones and can be sealed and used as tabletops and wall hangings, etc. Along with the necessary iron ore that triggered America’s Industrial Revolution, these ancient deposits are also producing amazing slabs of banded jasper-like rock that has been bent and curved in layers with alternating red, yellow and even black and metallic looking hues. One of the most historically important and largest deposits of banded jasper occurs in the Mesabi Range of the Upper Midwest where alternating bands of bright red to yellow iron-rich hematite and black magnetite or other iron oxides were deposited. ![]() Before such jasper hardens, some ground movement can bend or fracture these layers forming undulating shapes or curving images. In deposits of undisturbed layered volcanic ash, the ash takes on a linear form of varying layers of alternating color depending on the impurities that are present. Such attractive shapes are given names like poppy jasper. When these spherulites are exposed by the lapidary or are near the surface they have the shape and design of small, round flower-like inclusions. Such growth is not continuous as outside influences like heat and moisture can speed up or slow the radial growth. This process happens again and again everywhere within the jasper colloid as spherulites simply form wherever there is enough impurity to provide growth. Crystal growth happens in all directions and from all sides and results in the free form of a small rounded body called a spherulite. They can join on all sides because the original molecules are suspended. Once a few molecules attach, more molecules join. This is how mineral crystals get their start. As molecules form, they have a natural penchant to attract to each other. This is important because in such conditions impurities will have a long time to develop micro-crystals. ![]() When well insulated by later hot flows, the ash gradually develops a colloid-like structure that is semi-fluid. Pin this post to save this information for later. Given enough moisture and heat, the ash may become a clay-like material that is flexible enough to be influenced by ground movements that cause bending and folding of the layered clay. Studies of deposits of colorful jasper indicate that once volcanic ash has been deposited by wind or flowing water it may be reheated by later volcanic activity. Jasper is found in a variety of environments but is best seen in volcanic areas where it develops in and from volcanic ash deposits. In either form, jasper is slightly granular but is almost the hardness of regular quartz so it will develop a good luster when it’s polished.īecause it is rich in microscopic crystals of metallic oxide, mainly iron oxide, these impurities can infiltrate the stone and are dominant in jasper’s lovely colors with reds and yellows being the dominant hues. The difference is the size and arrangement of the silicon dioxide molecules. Jasper is basically quartz but its micro-crystals can vary from quartz to chalcedony. ![]() Since jasper varieties are found so widely, many are named after the location of discovery. It’s also found in a wide range of forms including banded, orbicular brecciated, curving and swirling. It is one of the more colorful and varied lapidary stones. Jasper stone varieties are found all over the world.
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