Fastest Way To Get Coal

Hey all, I need to get about 35k coal, I'm currently mining it at the Motherlode Mine and wondered if there was a faster way? I'm not a high enough combat level to kill bosses but I wondered if there was a set of coal rocks near a bank or anything or is the MLM the quicker way? Many thanks in advance

Edit: Thank you everyone for the advice, I'll be turning off comments now so I don't get swamped but honestly, thank you all