Source: The Silmarillion/appendices
Disclaimer: Tolkien discovered Middle-earth and wrote of all who dwell there.
It was a skill needing work. Her ‘seeings’ would not come of her choosing, some days, struggle as she might, no images could be discovered, in fire, dust, or wind-blown leaves.
Galadriel confided in Lady Melian about this un-sought ability. Thingol’s Lady had nodded and smiled.
“A gift is given… or a curse – we must see you use it wisely.”
The two would withdraw from the babbling fountains and courts of the citadel, travelling to Neldorath, where among the great beeches they found springs filling small pools… Here Galadriel found still waters, which, under Ithil, became her mirrors of fortune.