Also please read my article I need some urgent help with my hen
I checked out your article, but can't seem to get back to it, but this should help. There's an article here on BYC titled:
Common egg quality problems
Check out the part about calcium deposits on eggs. The example in the article is much more pronounced than what you're seeing, but looks like the same issue. It also looks like a pretty easy dietary fix.
Good Luck!