Coal is a happy sort of pony, mostly enjoying building things, relaxing at the pool, enjoying some good books from the Treebrary, and stargazing at night.
Coal would describe herself as a simple pony. Hard working, up for a bit of fun, and likes her romance books. She also loves sugary treats, but finds that sometimes, too many can make her....bouncy.
Coaldust was born in Caerfilly, a wealthy agricultural and mining town founded by earth ponies. Her family were coal miners and had been for several generations. This is mostly the cause of Coaldust's large build and stature. Her father spent most of his time working in the local coal mines, while her mother (to whom she refers to as 'me mam') helped ensure that work clothes were kept clean and food was plentiful and ready for the hungry workers.
Coaldust originally thought of getting into mining like her father, after finding her strength was useful for helping move much of the heavy equipment they used. However, one day, her father and several other miners were hurt in an accident when part of a tunnel collapsed. While no-one was killed, there were quite a few injuries and work was set back for some time. Coaldust spent time with her father during his recovery, before deciding the best way to help was to try and make sure such an accident wouldn't happen again.
Her studying turned from mining to constuction and engineering, planning and designing ways to set up mine tunnels that were more sturdy in the event of an accident. With quite a bit of nervousness, she submitted her design to the site foreman, who was pleasantly surprised to find her design would actually work very well. As the collapsed tunnel was cleared and the new tunnel work put in place, it was proclaimed sturdier and more secure than any other tunnel before it. At that point, Coaldust received her cutie mark - a pair of crossed hammers, showing her skill at expert construction.
Coaldust spent some time working with other builders, helping redevelop coalmines. She helped out with building new buildings, as well as renovating older ones. Through this, she expanded her skills to general construction. Once her skills had helped teach the other builders, she no longer had any work to do. As such, she decided to travel and see the world.
As she travelled, Coaldust visited many towns and cities before coming across Ponyville. It was there that she met the unicorn Dai Greenhoof. Recognising him as a fellow native of Caerfilly, she decided to hang around with him. He eventually introduced her to the Thunderhoof family farm. It was dilapidated and in need of dire repair, and Coaldust leapt at the chance to put her talent to use once more.
Coaldust's skills are based in the field of construction and engineering. Her size and strength also make her adept at pulling and lifting heavy objects, but she is not much of a runner as a result.
She also jokingly refers to her ability to put away large quantities of food as a talent, though it isn't really much more than a hearty appetite.
Coaldust is married to Dai Greenhoof.