Originally Posted by Nullific
Mescaline is undoubtedly one of the rarest hallucinogens to come by. Although it occurs naturally in several species of cactii some take years to grow large enough to yeild a single dose. It would be impractical to extract mescaline, considering the amount of cactus it would take for any large-scale mescaline tablet manufacture. Of course it can be synthesized but that would also be very inefficient for anybody looking to make a profit, keeping in mind that it takes a dosage of over 400mg of mescaline to produce pronounced effects.
Just take a look at ecstasydata.org which has tested over 1,500 tablets with GC/MS, none of them appeared to contain any mescaline whatsoever.
If you were told an "ecstasy" tablet contains mescaline it was more than likely just to arouse more interest in the user, or the tablet contains some research chemical such as a 2C-x or DOx.