The tears of the sun is a folk legend from the dwarves of Kuparöyk mountain, who derive their living from harvesting the copper crystals found there.
It is said that before they were born, the sun was lonely and cried for a daughter, and the tears fell onto the mountain, flowing like a river. The tears hardened in the cold of the mountain and formed the crystals the dwarves mine today.
Once a year on the 'sun's birthday' (what we know as midsummer) the dwarves hold a large banquet, toasting to the sun and giving their daughters small gifts- from flowers to jewels to books, anything. One daughter is chosen as the 'Kuparlass' or 'sun daughter' and remains a good luck symbol of the village all the year. The daughter is dressed in green- it is not known exactly why, though scholars believe that this may have something to do with the effect of saltwater (tears) on copper, turning it green. There are no dwarven sources to confirm this.
A related folktale to this states that should the Kuparlass ever cry during her year, her tears must be collected and poured onto the mountain. It has long become tradition for the women of the tribe to go to a cave under the mountain when one is in need of counsel.
(I'll be back later today with something more!)