Hrm... it's possible there's a bug with that rank of mining endurance. I checked base health levels against a guildmate with the +70hp tier of mining skill. His undead death knight had more health than my tauren - both at 80. Neither of us had spent talent points, had any gear on, or were in frost presence (we then checked frost presence and again, he had about 300 more health than the cow).
I wonder if the +70 hp version is incorrectly being awarded as +70 stamina.
-Splug
_________________
(Usually) Prot warrior:
http://www.wowarmory.com/character-sheet.xml?r=Illidan&n=Splug