Cast iron. Not affected by high temps as steel is affected.
An andrion is a metal supports for logs in a fireplace.
andiron
An andiron is a horizontal iron bar upon which logs are laid for burning in an open fireplace. They are used to elevate the logs from the floor of the fireplace to improve air circulation for better burning. Andirons also help prevent logs from rolling out of the fireplace.
The log holder is an andiron.
Brass knob similar to a small doorknob, used to move the andiron (fire-dog or log-rest) on which it is mounted. The andiron is mainly remembered in public consciousness now because of "The Adventures of Tom Sawyer" (1876): Tom was given a brass andiron knob as 'payment' for allowing a friend to whitewash the fence and as it was his most prized possession he gave it to Becky Thatcher (she returned it on discovering he had been 'engaged' to Amy Lawrence!)
A pair of metal supports that hold the logs. In ancient times they were sometimes made of natural stones. The function of andirons (or firedogs) is to provide more air to the fire, so that the fire burns better and more efficently.
A utensil for supporting wood when burning in a fireplace, one being placed on each side; a firedog; as, a pair of andirons.
cover the top with a piece of metal
The metal support used in a fireplace is called a "fireplace grate." It is placed inside the fireplace to hold logs and allow airflow for a better burning fire.
The left side andiron has melted!
A safe fireplace screen is made of metal but won't overheat when touched.
I would like to add a mantel to my fireplace. What is the best fireplace mantel configuration available on the market?