Cactus quartz is characterized by a large quartz crystal over which smaller crystals have grown. Usually this is amethyst, but this can also occur with citrine and smoky quartz or in a nice combination such as this cactus quartz in 'happy colors'
How does amethyst form?
Amethyst is a purple variety of quartz and owes its typical purple color to the presence of iron that is colored purple by the ionizing radiation (or radioactive radiation) of the earth.
The cactus quartz is also known as spirit quartz. It is a powerful healer where the energy comes through the main crystal and is radiated through the small crystals in all directions. Spirit quartz provides unity and is an ideal stone for group meditation to connect all energies.