hi warsur,
sorry for my late reply~ i am madly busy this few days.
actually, i dunno what the violet particles are.
by refering FS Koi stone, i noticed that there are some tiny violet particles. (not as much as the one in Japanese website!)
i can't make any conclusion here but the main point is ... "DOES THE VIOLET IMPURIFITIES GOOD FOR CRS?" hmm.... i dunno.
http://mineral.galleries.com/minerals/s ... ntmori.htm
it should be contains Na,Ca, AL, Mg, Si only, none of them are violet.
- should be white in color
- world wide product.
it is not surprise that Japanese have it owns 蒙脫石. in fact, HK also have 蒙脫石 mine. (it's true!)
just in different grade and size of it, like diamond, emerald and other gems.
i am still using FS 蒙脫石. it shouldn't harm ur shrimps, CRS as well. however, i GUESS it should be faster to be used up than ur Japanese grade 蒙脫石.
finally, show u my FS koi stone: