I am more than tense to hearing what nature these stones are.
By the way: Ho did you find a lab willing and capable to do this analyses? Would you be so nice giving the address of this lab.
Furthermore:
I am convinced that not only the productiveness of the flushes vary a lot but also the composition of the stones. Some members reported of easily melting stones. After having completed 21 lfushes I never ever passed melting stones. Furthermore, the colour, shape and texture of these stones are tremdousliy different. Some are perfectly round like a perl, dark in colour, others are very irregular in shape and whithish outside and green inside. Few are semicalcified.