In Elcarin culture, the kunmegg-nquj, or "five noble substances", are marble, quartz, gold, iron and silver. The root kun means jewelery, coins, and similar items, and kunm is a substance from which such things are made. The suffix egg means "noble", and nquj is the Elkarîl word for "five". The five substances are, of course, not used exclusively to make kun - for example marble is used in architecture and iron for weapons.
The discovery of these substances predates history, but accounts are found in mythology. This includes Elcarin sources, but the most familiar example is the Cuêzi Count of Years. If we believe this, then marble and quartz were simply stumbled upon, the latter when an Elcarin miner looking for marble threw a purple stone against the wall in frustration. Elcarin sources agree with the Count of Years that their first encounter with gold was through the jewelery of a visiting Iliu on pilgrimage, but the Elcari took a characteristic interest in inventing techniques for searching for it. Iron was apparently discovered during the arms race against the Múrtani, and is called the revealed metal because it was hidden in front of Elcari noses until they learned to refine the ore. Silver is called the metal of the moons, and was discovered after iron tools made mining more efficient.