Muckish, Mountain summit in County Donegal, Ireland.

Muckish is a mountain in County Donegal with a summit at about 666 meters, marked by steep slopes and a broad, flat plateau covered in quartzite rock. The white color of the stone stands out clearly from the green surroundings.

High-grade quartz sand was mined on the northern flanks of Muckish and exported mainly for making optical glass; the quarry workings remain visible there. The Miner's Path to the summit partly follows the route the quarry workers took. A 2012 documentary, "Glass Mountain: The Story of Muckish Sand", recounts this sand-working past.

The name comes from Irish 'An Mhucais', referring to the mountain's shape resembling a pig's back when viewed from the landscape. Visitors can easily spot this distinctive outline from various points in the surrounding area.

Two main routes lead to the summit: the Miners' Track from the north and a path from Muckish Gap on the south side, each offering different challenges and views. Visitors should watch for weather changes and bring appropriate gear, as cloud cover can develop quickly.

The quartz sand from Muckish's northern quarry was exported and used mainly to make optical glass, which earned the mountain the nickname "Glass Mountain" and inspired a 2012 documentary of that name. The Miner's Path to the summit partly follows the route the quarry workers took.