This large Ethiopian Opal is a hydrated amorphous form of silica. Opals have one of the highest water contents of any mineral, up to 20%. In the Middle Ages, opal was considered a stone that could provide great luck. It was also said to grant invisibility if wrapped in a fresh bay leaf and held in the hand. In general, opals are said to inspire creativity, inventiveness, spontaneity and self-expression. They can help you lose stifling inhibitions, freeing your wild and adventurous side. It is a passionate stone linked with love, desire and lust.