How many grams of beryllium are in 147 g of mineral beryl?

The number  of Beryllium that are in 147g   of mineral Beryl  is calculated as below

find  the  moles of mineral Beryl  = mass /molar mass

molar mass  beryl mineral (Be3Al2Si6O18)= (9x3) +(27x2) +(28 x6) +(16 x18) = 537

= 147g/537 g/mol = 0.274 moles  of Be3Al2Si6O18

find the  moles Be  in Beryl mineral

that  is   3 x 0.274=0.822  moles   since there  is 3  molecules  of  Be in beryl  mineral

mass of Be is therefore =moles of Be x molar mass of Be

0.822moles x 9 g/mol  = 7.4 g  of Be