||Jasper is derived from the Anglo-French "jaspre", meaning "spotted stone". Jasper is usually formed from old sediments (or volcanic ash flows) that have been glued (and at times replaced) with silica.
Flow patterns of the original material are often easy to see. Many jaspers are know as picture jasper because they contain what appear to be small images of sand dunes, mountains, plains, and even sky. Since the original materials were likely cross bedded sediments, they often contain the structure they mimic.