Antique Cast Iron Fireplace Surround Frame

total measurements just shy of 30.25" height x 24 5/8" width x 3.25" depth
inner measurements just over 24.75" height x 18" width
(US dollar bill shown in image for size comparison only)

Antique, pre-owned condition, salvaged, some surface wear and loss, flaking to paint, some surface rust on back, fireplace residue is present. See photos.