The Rarest Mandarin Syllables
Introduction
From September 2019 through October 2020, I catalogued the rarest syllables of Modern Standard Mandarin. Occasional notetaking turned into a systematic search, and I believe this list is close to complete. To the best of my knowledge I am the first to compile much of this information -- but perhaps others have done so, somewhere beyond the reach of my search-fu.
During this investigation, I was specifically concerned with syllables which are rare regardless of which tone they are pronounced in. This meant that even certain uncommon tone-syllable pairings were not rare enough for me; for instance, only two characters are pronounced qiong in fourth tone, but qiong was not eligible for my list because there are many other characters pronounced qiong across the other three tones.