Jean Louis and David,

Thanks.  That's amazing.

> For 100 grams:
> i.e. roasting destroys 100*(354-129)/354 = 64 per cent of the magnesium.

I find it interesting that the two different recent posts have such
different content for sea vegetables.; one lists laver with 2 vs 378 mg
of magnesium; the other says 121 vs 900 mg in kelp; both are supposed to
be for 100 grams.  I wonder why it is such an obscure piece of
information with such a variance.