Meaning, History, Applications, Healing Properties, and Maintenance of Blue Agate Jewelry Blue agate belongs to the quartz band of minerals and is a chalcedony, like other agates. Agate knobs grow in volcanic stone or lava, as well as in filled veins or fissures. Iron shade may be used to color a variety of agates to create a blue tone. The key to the significance of blue agate is power, recuperation, profundity, confidence, and tranquility.