Repeatedly calls Template:Atomic mass to determine the molar mass. Maximum of 8 elements.
{{Molar mass|Fe|2|Si|1|O|4}}
= 203.771{{Mm|Fe|2|Si|1|O|4}}
= 203.771{{Molecular mass|Fe|2|Si|1|O|4}}
= 203.771{{Molar mass | Fe | 2 | {{Molar mass|S|1|O|4}} | 3}}
= 399.858