Yes, this behavior is intended.
The simple reason is because of how sporadic mining can be.
In OSI days, mining was a static operation, where ore would respawn in the same location, over and over again.
Here on UOE, ore respawns at random; which makes mining in the same location-- for the same special ore-- twice rather unlikely to be a success.
In the end gathering any specific (colored) ore type, beyond regular, is on a balanced scale of 'unsure'. This fact is good for the economy, since everyone mining throughout the day has the same chances of finding what they truly want/need as everyone else.
In order for there to be a balance, with the hammers you mentioned, supply and demand must be factored in. Of course, when the charges, on the ancient hammers, are used up-- due to successfully crafting something of value, or the opposite-- the supply has been used up and a demand for more hammers/charges is factored in. In order for you, the craftsman, to get more (ancient hammers) you'll either have to find more-- through playing/hunting, or buy them from other players. This, in effect, is economics 101, and without it... anything crafted on the shard would have little value.
I hope this helps. Sorry if it is more then was required. Also, I probably skipped a few steps when it comes to Economics 101, but I slept through most of that class.
--Sturger--