I've just checked "The Coalfields of Scotland" published in 1902 which deals with both Coal and Ironstone mining and Blairdardie doesn't even get a mention suggesting that it was no longer operational by about 1900.
Upon re-reading the article regarding the 1871 sale it mentions that the new owners expect "commencement shortly" and I wonder if the coal works had been shut down and the new owners were going to start mining ironstone. If so it wouldn't have been good news for the miners who would have been out of work (and housing).
(Although the same workers could easily mine Ironstone rather than coal it was unlikely that they would have been kept in employment during any shutdown period and of course with tied housing their families would also have been made homeless)
Another Book published in 1920 has several mentions of Blairdardie but generally regarding the geology of the mine
The Economic Geology of the Central Coalfield of Scotland
by
Lionel Wordsworth Hinxman, Ernest Masson Anderson, Robert George Carruthers, Geological Survey of Great Britain
which can be found at
www.archive.org