I leveled archaeology to 450 on my dk saving all my troll fragments and tablets until i hit 450. I hit 450 and had 1469 fragments and 32 tablets which equated to 57 solves and no luck. I know some people have gone 200+ solves and still nothing, but I don't want to be in that boat and nothing to show for it. I'll keep solving troll artifacts but I really hope blizzard does something about this, yes I know it's a rare artifact however...
Archaeology is the only profession that may not pay off (or not pay off in the way you want it to) after investing hours or days into it. If you want two extra sockets you invest time and thousands of gold into blacksmithing, if you want extra stats from gems you level jewelcrafting, if you want to cook your own food you level cooking, if you want to catch fish you level fishing. If you want the best 2h strength weapon in the game before nefarion and you dont raid or it's your alt which will never see nefarion, you level archaeology, but instead of finding the one rare artifact which was the sole purpose of leveling archaeology, I got dancing dwarves and a crummy mirror.
I know what a lot of people are thinking, yes it's a rare drop it's not supposed to be easy to get, and I agree, but when people have 200+ solves (plus the solves from dwarf, fossil, and the odd nelf artifact) and still don't have Zin'rokh, there's a serious time invested per payoff issue here, and if you're still telling those people with 200+ solves to QQ more then it means you dont want the sword, or already have it.
It seems the solution is simple, the more solves you have of a race, the greater the chance of finding the rare artifact(s) of that particular race. It preserves RNG so all those lucky people who get it 2 solves after 450 and gloat about it can still do so, but also means less and less people going hundreds of solves and hours without finding it. Maybe even after a certain amount of solves it becomes a guaranteed drop, to prevent those incredibly unlucky people from never seeing it.
edit: up to 116 troll solves post 450 and still nothing