Letovicite
Letovicite is an ammonium sulfate mineral with composition ( NH4 ) 3H ( SO4 ) 2 ( IUPAC: triammonium sulfate hydrogensulfate , Nickel–Strunz classification 07 . AD . 20 ) . 
<triplet> Letovicite <subj> sulfate mineral <obj> subclass of <triplet> sulfate mineral <subj> Nickel–Strunz classification <obj> part of the series