'''Opal''' is a type of silica mineral. It is often valued as a jewel, although it is less valuable the the diamond. It was once highly valued by the Romans. During the [[Middle Ages]], it was thought to bring good luck, but now is considered the opposite. It is the birthstone of September.
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'''Opal''' is a type of silica mineral. It is often valued as a jewel, although it is less valuable the the diamond. It was once highly valued by the Romans. During the [[Middle Ages]], it was thought to bring good luck, but now is considered the opposite. It is the birthstone of October.