Correct spelling for the English word "kapnite" is [kˈapna͡ɪt], [kˈapnaɪt], [k_ˈa_p_n_aɪ_t] (IPA phonetic alphabet).
A variety of zinc spar, containing more than 15 per cent of iron protoxide.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.