Foil that is used is just that, thin metal sheets of silver, (most common) although gold foil is used on occasion.
Mica is a naturally occurring mineral of the sheet silicate family, known for it's ability to split very into very thin sheets, This property is referred to basal cleavage.
Aventurine is technically the result of a process involving the creation of copper crystals within glass, which are then used in pieces in other glass. This term is also been commonly applied to the use of metal particulates in glass, most commonly Italian glass. It is a term that through misapplication has taken on a broader common meaning when referring to glass in a non technical terms. The use of gold powder or silver foil within some glass is referred to by many as "Aventurine", although "technically" the use of that term would not be correct to describe those decors, but it has become for many, a commonly accepted term.
Glitter, is what you glue to a greeting card, jewelry, clothing, and many other things to make it sparkle.... Usually purchased at a hobby or craft store, it is generally made of a plastic material, and if you were to introduce it to molten glass would burn almost instantly contaminating the gather.
Pictures below are in the order of descriptions, except I do not have any glitter....