These appear to only be used for buying power sources, whereas phosphenes are the currency for armor/weapons from the elite vendors. Its also worth mentioning that after about a dozen kills of random trash in the zone, I didn't have a single mob that didn't drop between 1-5 phosphites at random.
i believe they are. from what i remember the phosphite/phosphene drop from bosses in "clusters" (Phosphene Cluster, Small Phosphene Cluster, Tiny Phosphene Cluster) , which are then opened and distributed by the raid leader or such.
so they are tradeable, but i doubt there will be any for sale soon as players will want to be using them for the uber gear/spells
you actually have to "unlock" gear as well. if you notice, or were able to get some phophites or phophenes, you cant buy anything with them, because it doesnt come up on the elite merchant list. being in a raid that defeats solteris missions will unlock different items. solteris1 is bracers, two is hands iirc, etc