Slight spoiler for Wheel of Time book 2: The Great Hunt
. . . . .
In The Wheel of Time, I understand production and the need for weapons 'n things, but why do the Seanchan value damane who can locate ore so greatly?
Egwene is highly valuable because she can locate ore. This appears to be a test all sul'dam perform on new damane. It seems to have a higher value than that of the continent east of the Aryth Ocean (I don't actually know the name of the main continent), but why?
Finding ore using the One Power is a Talent and requires an affinity with Earth, something which has been dying out this side of the Aryth Ocean (slightly less so than on Seanchan). Egwene is strong in Earth and is one of the very few damane who can find ore using the One Power.
“Apparently,” she said bitterly, “I am now too valuable to be wasted making things explode. Any damane can do that; only a handful can find ores in the ground. Light, I hate making things explode, but I wish that was all I could do.”
The Great Hunt: Chapter 42 - "Falme"
It is not a test all damane go through, Egwene notes that testing her for this didn't occur to anyone before because typically :
"No one even thought to test me on this earlier. Earth is one of the Five Powers that was strongest in men."
The Great Hunt: Chapter 42 - "Falme"
In short, the value and usage of the metal is pretty much the same on both continents. However, the Seanchan value the damane rather than the ore itself. If you have a damane who can sense buried pockets of valuable metal, you can use that damane to bring it all up and refine it as well.
