1) Mr (Ca3Al2Si3O12) = 40*3 + 27*2 + 28*3 + 16*12 = 450
W (Si) = 84\450*100% = 18/6%
2) Mr (SiO2) = 28 + 16*2 = 60
W (Si) = 28\60*100% = 46.6%
3) Mr (CaMgSi2O2) = 40 + 24 + 28*2 + 16*2 = 152
W (Si) = 56\152*100% = 36.8%
Ответ: в кварце больше всего кремня.