What does insert mean in these listings?

It's the metal unit that sits inside the fireplace opening, as opposed to the surround that frames it. On Sellingantiques the heading stretches wider than that, taking in grates, baskets, fronts and complete fireplaces. Dealers often don't use the word at all. Grate, basket, inset, front, surround and combination all appear in titles instead.

Which type turns up most often?

Cast iron. "Cast" and "iron" run through the titles, and the Victorian cast iron insert or grate is the recurring form, whether register, combination or tiled. The commonest single pattern in the samples is a cast iron insert paired with a marble fire surround, listed as a set.

Are copper fireplace pieces unusual?

Copper turns up more often than you'd guess for a fireplace metal. Four sampled titles are copper, two of them dated 1910, including an embossed insert and an Arts and Crafts fire front with a hood canopy. Worked copper sits higher than plain. An embossed copper insert reaches well up the range.

How old are most of these?

Dating is broad. "19th Century" is the largest single entry, with Victorian and Edwardian behind it, so those read as period attributions rather than years. Only eight listings carry a clean year, and those fall between 1880 and 1930. Decade labels cluster at the 1910s, with the 1880s and 1920s behind. Georgian, Regency and 18th Century entries each appear once.

Does the surround come with the insert?

Sometimes. Around a quarter of sampled titles pair the two, in marble, oak, mahogany or painted pine, and one 1930s surround is a mirror. A pair of surrounds sold with their inserts is the rarest configuration in the archive, appearing once.

Why do so few of these come up?

It's a small and slow category. About four come to market a year on Sellingantiques. Eighteen different dealers have listed one, close to a single piece apiece, so it isn't a field anyone stocks in depth.