Although coal mining is an activity traditionally associated with the Central Lowlands, Lothians & Fife, coal has at times been mined as far north as Brora in Sutherland in the north, and as far south as Canonbie in Dumfriesshire, where my Innes family lived in the 1860s and they worked in both the railways and coalmines.
There have also been coal mines on Mull and at Campbelltown on the Mull of Kintyre.
If you know of any other coalmines outside these areas I'd be most interested in finding out more & would appreciate it if you'd email me with your findings.

Ian Winstanley has lists of collieries active in Scotland in at various periods throughout the 19th and 20th centuries, these can be viewed at his Coal Mining History Resource Centre

 Clicking here will take you to a list of mines active in my home county of Lanarkshire in 1896.

My hometown of Blantyre in Lanarkshire was infamous for being the site of Scotland's worst mining disaster when approximately 220 men and boys were killed on the 22nd of October 1877.
And this page here has a list of miners killed in the pits of Blantyre. Be warned however the page is very large, so will take a wee while to load!