Below you will find a good rule of thumb for makeup expiration dates. Remember, however, that mineral makeup keeps it's integrity for about double the time of liquid or other powdered makeups.
Foundation - 12-16 months (mineral foundation- 24-36 months)
Powder- 18-24 months
Mascara - 4-6 months
Concealer - about 12 months (mineral concealer- 24-36 mos.)
Lipstick - 12-16 months
Eye Shadow - about one year (mineral eyeshadow- 24-36 months)