agate is a common stone formation, consisting of chalcedony and quartz as its main components, consisting of a wide variety of colors. agates are primarily formed within volcanic and metamorphic stones.
Howlite is a borate mineral. This stone may be known as an imitation gemstone because it can be painted with different colors and looks like semi-precious gemstones such as turquoise and coral. Howlite is often inexpensive, but it has many features that make it a popular gemstone in jewelry.