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.
The mineral magnetite is iron oxide (Fe3O4), which is found in all three igneous, metamorphic and sedimentary rocks. This stone is often extracted from iron ore. Magnetite is also a mineral with the highest amount of iron (72.4%).