Tungsten Ore is a rarely generated ore created by Redpower. It can spawn at any level of the map, regardless of depth.
Currently, it has no worthwhile uses other than as an excellent source of EMC in Equivalent Exchange. It is valued at 16,384 EMC, making it worth the equivalent of two Diamonds.
Tungsten Ore is usually found in clusters of 1-2, and rarely found in groups of 3-4.