Fire Agate, a variety of chalcedony is a semi-precious natural gemstone found only in certain areas of northern Mexico and the southwestern United States.

These areas were subjected to massive volcanic activity during the Tertiary Period. The fire agates were formed during this period of volcanism when hot water saturated with silica and iron oxide repeatedly filled cracks and bubbles in the surrounding rock.

Fire agates have beautiful iridescent rainbow colors, similar to opal. Its hardness on Moh’s scale is between 6.5 and 7. This prevents fading, cracking and scratching of the gemstone.

The vibrant iridescent rainbow colors found within fire agates are created by the Schiller effect as found in mother-of-pearl. It is caused by the alternating silica and iron oxide layers which diffract and allow the light to pass. This light forms colors known as fire due to interference.

There is no actual object inside the stone. This special effect arises from light interference within the micro structure layering of the gem.