The Greek origin of the word jasper, iaspis, means "spotted stone." This form of semiprecious chalcedony, or microcrystalline quartz, is usually red, brown or green. Its patterns are much less regular and defined than those of the other chalcedony variety, agate. Another difference between the two is that jaspers are generally opaque, while agates tend to be translucent (or at least contain translucent bands). This distinction stems from the stones' composition. Jasper contains microscopic "grains" of crystalline quartz and agate has microscopic "fibers" of crystalline quartz. Although the term jasper is often applied to unidentified stones, true jaspers are metamorphic rocks.Jasper derives its colorful patterns from other minerals present, and is often named according to its pattern. It has a dull luster but takes a fine polish, and its hardness and other physical properties are those of quartz. Jasper is often sealed with petroleum products. Its polish might wash away in water, so clean with a soft, dry cloth.
The gem was a favorite in the ancient world, and the name jasper can be traced back in Hebrew, Assyrian, Persian, Greek and Latin. In the fourth century, it was called the great "rain-bringer," and it has been thought to strengthen the stomach and cure gynecological troubles. Some also use it to drive away evil spirits and protect against snake and spider bites. It supposedly gives you the courage to speak out and the bravery to achieve personal independence. Landscape jaspers are amongst the most popular varieties. Jasper is mined in North Africa, Sicily, France, India, Venezuela, Germany, the U.S.A. and elsewhere.