I am making silver blue wheaten Marans. The nicest silver blue wheaten pullet has been laying a good dark egg (a nicer colour than the other two slver blue wheatens). Within the last couple of days this pullet has started laying her eggs with that chalky whitish deposit which, if moistened, shows the usual colour of the egg but still dries chalky. Previously I just wouldn't have used any eggs like this, but as she is the nicest pullet with the best eggs in the project I don't know what to do. How does this affect the eggs? Is it a hereditary trait? Are such eggs even hatchable?