Hi, Jon.
Jon writes:
I am unfamiliar with any other orthography that regularly employs both and , except in loanwords...
I think most of the Germanic orthographies do. Danish/Norwegian maybe doesn't.
Swedish does, though. And, both "c" and "k" can be used for hard "k" sounds before hard vowels, but diverge before soft vowels: "k" is pronounced "sh" and "c" is pronounced "s" (as written in English) before soft vowels. They also use "ck" for a hard "k" sound in some words (e.g.,
flicka, "girl").
Mandarin Pinyin does, too.
-Bluejay (a.k.a. Mantis, Thylacosmilus)
Darwin loves you.