8g, 1.5" x 1". Acquired from a private collection in Arizona. Fire agate is a semi-precious natural gemstone in the chalcedony family. It is found in areas of the southwestern US and in central and northern Mexico. Fire agate was formed 24-36 million years ago during the Tertiary Period. It is between 5 and 7 on the Mohs Scale, and has beautiful iridescent colors.