Incense crystals were also known as Land Spirit crystals.
This substance can only be created by Land Spirits. Previously, these crystals had been monopolized by the Land Spirit Alliance. They were partly the reason why the Alliance became one of the most powerful forces around the globe.
During the Dharma Ending Age, Land Spirit crystals had been called incense crystals because of the severe shortage of reiki during that time. Instead, they had used large amounts of incense to make incense crystals. However, when the era of recuperation of reiki came about, reiki had been plentiful in the world. The sheer abundance of reiki had aided the Land Spirits in the creation of Land Spirit crystals easily with small amounts of incense and large amounts of reiki.