all stop consonants (and most other letters) can appear geminated in (written; not spoken) english, with the exception of ⟨k⟩, for apparently no reason at all. in the contexts where k would normally be geminated, instead of writing ⟨kk⟩, you write ⟨ck⟩ for some reason. ⟨cc⟩ is still fine too; it can be seen in words like occur and accord.
I wonder why that is?