How often do Gothic chests come up for sale?

It's a small category. About four come to market a year on Sellingantiques, and 28 different dealers have listed one, so almost nobody carries two at once. That spread also means the forms vary from listing to listing rather than repeating.

What timber are they usually made from?

Oak dominates. It appears in 18 of 33 titles, and the pairing "oak coffer" accounts for 10 on its own. Walnut, chestnut, elm, mahogany and rosewood each turn up singly. One title says only "hardwood", without naming the species.

Are these all medieval pieces?

No. Roughly a third of the samples are early oak from the 16th and 17th centuries or earlier, described as circa 1540, circa 1600, circa 1680 and one late 15th century coffer in oak and elm. The rest are later. About a quarter are 19th-century Gothic Revival chests, and around a fifth are Arts and Crafts coffers with Gothic carving, dated between 1880 and 1940.

Why do the dates in the listings look so vague?

The dealer date field is mostly a period label rather than a year. "19th Century" appears eight times, "16th Century" four, and there are single entries for Victorian, the 1870s, 1880s, 1900s, 1910s and 1920s. One reads simply "Select". Only nine of 33 listings carry a clean year, and that field runs 1750 to 1940. The titles reach much further back than the field does, which is why the early end looks thinner than it is.

Do continental chests appear in this category?

More than the Gothic oak heading suggests. Spanish, Italian, French, Swedish, German and American pieces each appear once. Among them: a Spanish painted blanket chest with Moorish decoration, a Spanish Gothic cathedral chest, a Westphalian iron-bound coffer with an inscribed date, and an Italian gilt Gothic walnut cassone.

Which forms besides coffers turn up?

Iron-bound strong boxes and deed boxes are the largest side group, six of the sampled titles, including a ship's carved oak and steel bound strong box and a French chestnut deed box. Blanket and dower chests appear too. A few forms show up exactly once: an Arts and Crafts iron log bin, a rosewood Gothic Revival canterbury, and a small carved elm lidded box.