For a basic competence on opal terminology, the two kinds of opal are: common opal and precious opal. Common opal has no fire or inner brilliance. Precious opal is any opal that displays fire, no matter the color of the fire. Opal body types range from transparent to non-transparent or opague. Precious opal and fire opal are not interchangeable terms. Fire opal is a term reserved for opal that is transparent with a saturated red to orangish-red body color and predominantly green and red fire. The very fine speciment of fire opal depicted here was mined in Mexico.