The rugs are fire retardant. If an ember lands upon a rug comprised of anything other than wool, it will essentially melt the fibers causing a hard black spot on the rug, but the rug will not burn. The wool rugs will also not burn, but when wool fibers come into contact with an ember, they will not leave a black spot or mark. The fibers will simply turn to ash, but there will be a spot left in the tuft of the rug where the fibers will be shorter than the rest.
If your installation is calling for something heat resistant, you may be in need of a Hearth or Stove Board.