Azurite on malachite is formed from the oxidation of copper ores. Over time, as it absorbs water, it changes into the mineral malachite. Thus, the two are found together, creating a brilliant deep blue stone with flashes of green.
Opal is a stone of sympathy and compassion, pure thoughts & confidence. It is the most unpredictable stone, a symbol of ever-changing fortune. According to legend an opal talisman boosts foresight--dunno about that but it is my favorite stone.