Rachel sent this card from Mt Errigal, it is the highest peak in Donegal at 751m. It is especially known for its beauty at sunset when the quartzite crystals on the bare rock catch the light and give the mountain its pinky glow.
Quartzite used to be sandstone before it was crushed and heated under immense pressure by tectonic forces. And sandstone itself used to just be sand, perhaps an ancient sandy desert or the ocean floor, solidified and turned to stone by eons of time.
The photograph below shows a large slab of polished quartzite, intended for sale as a kitchen counter top. Quartzite can be different colours, red or pink tones show where there is iron. It is exceptionally hard and tougher, stronger than granite or marble for instance. This example shows the crumpling of its layers that occured as it was formed: