Good china is made with kaolin, clay with an ample amount of kaolinite. Wiki's pretty clear that “kaolin” derives—via 18th-century French Jesuit mangling of gāolǐngtǔ (高嶺土)—from the village of Gaoling in Fuliang County near Jingdezhen in Jiangxi.¹²*
From its first appearance in English in 1727, though, it was paired with a second ingredient variously transcribed as petunse,³ pih-tun-tsze,⁴ pai-tun-tsze,⁵ petuntse,⁶ &c.
Wiki does have an article on that, too,⁷ but it's nonsensically sourced & can't link to a Chinese article or back up its claim that the actual Chinese term is báidūnzì (白墩子).[citation needed]† Instead, most English sources just repeat different variations of old Encyclopaedia Britannica articles repeating updated forms of what the Jesuit called the stuff.
Meanwhile, 白墩子 doesn't appear at all on the actual Chinese Wiki and it only shows up on the shanzhai Chinese wiki as some Mongolian nitrate-laden salt.⁸ The Chinese Wiki article on hard-paste porcelain—the process they used at Jingdezhen—just says it involves gāolǐngtǔ and chángshí (長石).⁹ The Hong Kong Maritime Museum¹⁰ and a handful of other sites do mention the porcelain stone petunse but say it's a transcription of báidūncí (白墩瓷) instead. Under the heading pĭh tun tsze, Robert Morrison's 1819 Dictionary of the Chinese Language gives 白墪子 but with a 敢 and 子 in the top half of the central character instead of 敦... and with the note that "the characters are doubtful."¹¹
I assume the basic chemistry is right and a feldspar-rich stone was used to create Jingdezhen porcelain, but what is the way Chinese actually historically and presently talks about that stuff? & does anyone have any firm source for what term François Xavier d'Entrecolles was trying to transcribe?
* Although strangely enough, the article on "Jingdezhen pottery" itself has absolutely no mention of the materials used to create it and seems focused on establishing the exact provenance and chronological order of the pieces in the British Museum collection. Go figure.
† Naturally, the page's Wikidata entry not only doesn't include any Chinese, it exclusively includes the atonal pinyin romanization baiduncai in its English list. Since that's the only appearance of "white lump vegetable" on the internet, though, it's obviously unintentional vandalism by someone misunderstanding the Jesuit ts as a modern pinyin c and is easy enough to fix. [Done.]