Is there any reason for choosing a quartz crystal with or without metal lid? Some datasheets (this one for instance: link) claim better EMI performance and other do not write at all about it. So is there a reason I should choose quartz crystals with metal lid over crystals in a wholly plastic package? Here is what I have found on that topic: link
I am aware, that the second link is about a quartz crystal oszillator but I have not found anything else.
Considering the answers so far, especially the second one, I understand that shielding of the quartz itself is not needed. But then I am wondering why the quartz's manufacturer states the following (see first link and there note 2):
Terminations #2, #4 and the metal lid are connected internally. End user may connect these pins to circuit ground for EMI suppression.