I have borrowed this description from another seller on the Internet (The Metaphysical Stuff on Etsy), since she seems to be a specialist, and this is clearly the same item:

"RARE 1880s/90s English British 19th Century Antique Cast Iron Miniature Fireplace Grate Hearth Doll's House suitable for the English Silber and Fleming Box Back Doll's Houses..... nice detail and nice forms"

All I can add is that it appears to be cast iron and enamelled, and in very good condition, as per the photographs.

It's 6cm high and 6cm wide.