Quote Originally Posted by Kirk Keyes View Post
Well known? - didn't you just point out that there are two different specs for the same grade of borax? Granular and powder - both called Technical Grade, have differing specs?? That's pretty precise!

Also, you say,

That's not the highest grade that you have seen. Technical grade is usually considered the lowest grade. Surely you read the assay that Mick listed for the results of his ACS Analyzed Reagent Grade Borax - it listed "Assay = 99.101%". http://www.apug.org/forums/forum37/4...tml#post556946

Let's think about that for a second to let it sink in... One grade has a precision of 5 digits, the other grade has a precision of 10%. Now which one should we consider to be the higher grade? I hope you answered this one by saying "AR Grade" to yourself.
The highest grade I have seen from Rio Tinto specs is NF, a pharmaceutical grade, which lists only heavy metals at <20 ppm. The difference between Rio Tinto Tech granular and powder is ONLY in the water insoluble particles, which are <400 ppm in the granular and none in the powder. The variance in measurement of percent borax decahydrate is in the water content, which will vary with storage conditions due to changes in humidity. the same variance can occur in any grade, including AR.

Your AR grade assay was for a particular sample of known hydration