H/T Mental Floss.
Bone China does contain bone no big surprise.
Maybe you assumed that bone china was so named because it’s vaguely bone-colored, or because it’s sturdier than other types of dinnerware. Maybe you’ve never thought about this at all. Whatever the case, we regret to inform you that the bone in bone china is more than just an evocative descriptor. Bone china actually does contain bone.
Basically, the bones are calcined, or heated to a high enough temperature that there’s nothing organic left in them. After that, they’re pulverized into a powder known as bone ash, which contains calcium, phosphorus, and oxygen. Not only does bone ash help china hold up better against chipping, it also gives it a translucency that makes it seem extra delicate. This quality is also a good way to tell if your bone china is bona fide; as The Spruce Crafts explains, the outline of your fingers should be discernible through the porcelain when held in front of a light.
Bone china is a much more recent innovation than other kinds of china. British artist Thomas Frye and his colleagues experimented with bone ash at his porcelain factory in the mid-1700s, but it didn’t become popular until potter Josiah Spode II started using it in his products around the turn of that century. According to the Spode Museum Trust, Josiah Spode I, also a potter, had first incorporated bone ash from ox bones into his porcelain in 1796, and the younger Spode took up the mantle after his father died the next year.
It only took about a decade for bone china to catch on among other British porcelain makers, and the trend eventually arrived in the American market, too. In fact, Spode II’s material proportions—six parts bone ash, four parts china stone, and 3.5 parts china clay—are still considered the customary way to produce bone china. These days, you can buy synthetic bone ash, but it might not be quite the same as the real thing. “Because calcined bone has certain properties that are difficult to synthetically recreate, the material is still manufactured,” The Ceramic Shop explains. Theirs is made from cattle bones.