Hangeul Day(한글날) is a national Korean commemorative day marking the invention and proclamation of Hangul, the Korean alphabet, by the 15th-century King Sejong the Great. It is observed on October 9 in South Korea.
Written by Icelandic composer Jón Leifs in 1964, the piece called Hekla, Op 52, requires four sets of rocks hit with hammers, steel plates, anvils, sirens, cannons and metal chains to play.
15