You're in luck with a 1871 census entry which includes John's mother Christian. Here they are:

Malew, District 4, Folio 129, Page 11, Schedule 47
5 Close Clarke
John Cain, Head, Mar, 30, Lead Miner, b Malew
Jane, Wife, Mar, 33, b Malew
Ann J, Daur, 7, Scholar, b Malew
Christain [sic], Daur, 4, Scholar, b Malew
John, Son, 2 wk, b Malew
Christain [sic], Mother, W, 70, Ag Lab, b Marown

Cheers,
Ruth