Onyx is a chalcedony, which is a variety of the microcrystalline quartz. It is formed when silica is deposited in lava gas cavities. This results in the unique bands or stripes that Onyx stones usually exhibit. Onyx is often a black stone, but there stones that are brown, pink, red, green, or even colorless. Onyx can open the chakras and allow the better flow of positive energies. Care Instructions Detergents and lotions can damage the finishing and colour of the stones / crystals. * Clean with soft 100% cotton. Disclaimer: The information provided is intended as a reference of the metaphysical and healing energies of the crystals. Their healing powers are not established and cannot be guaranteed. Crystals should never be used as a substitute for conventional medical or psychological treatment.