Agate is formed with bands of microscopic Quartz crystals. It is a variety of Chalcedony. Agate is a grounding stone as well as a spiritual stone, allowing for one to bring their spiritual experiences into their everyday reality. Yellow Agate has all the properties of Agate, with the additional properties of the colour yellow, which include increased willpower, concentration, memory and logic. Agate (like most other gemstones) comes in a variety of colours, such as red, yellow, pink, blue, orange, black, gray, rainbow (multi-coloured) and even banded.