I just find it odd that crystal cannot be harvested until Crystal Weapon tech becomes available.

This is funky as you have to research Crystal Armor BEFORE the weapon tech, so a bunch of time developing a tech tree to harvest a material you cannot even use until way late in the game (In terms of crafting).

Would rather see an earlier Tech to allow Crystal Mining followed by the Crystal combat tech.  As for the Crystal combat tech itself having the ability to create lesser crystal Weapon/Armor enhancements that don't require the super rare Elementium would allow players to invest more heavily into that portion of the tech tree rather than all in civics/materials/metals.  Lesser Crystal arms/armor should be less powerful than their metal counterpart and perhaps require an expenditure of mana in order to forge troop items.