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Agate is a striped chalcedony quartz that forms in layers and in a wide variety of colors and textures. An individual agate forms by filling a cavity in a "host" rock. As a result, agate often is found as a round nodule, with concentric bands. In ancient times it was said to quench thirst and guard against fever, and agate bowls were very popular in historical Europe. Jasper is opaque chalcedony quartz that comes in a wide variety of colors and patterns, depending on the trace minerals present in the stone. Landscape jasper, which seems to show miniature earth scenes, and ocean jasper with its characteristic green swirls are both popular. Jasper was used for decorative and medicinal in many ancient cultures and the Babylonians believed it was beneficial to women's health. Opaque and royal blue with white veins, sodalite is found all over the world, sometimes in huge deposits. Often mistaken for lapis lazuli because of its color, sodalite has been used for decorative purposes since Egyptian times. Today, in addition to its decorative uses, a sodalite solution is used in some commercial swimming pool test kits. Royal blue lapis lazuli comes from the silicate mineral lazurite. Polished stones often show gorgeous veins of white calcite and flecks of golden pyrite. Used by ancient civilizations from China to Sumeria, lapis lazuli inlay adorned the mask of ancient Egypt's King Tutankhamun. Lapis lazuli is somewhat rare and much of the deepest blue stone is mined in Afghanistan. Denim lapis has a lighter blue color and Aztec lapis features dramatic veining of black and brown minerals.
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