I believe the subject is the young Mozart
Plaster Bust of a Young Mozart,16.5" high, Paris, Triarn Tiarn,over 9 lbs | eBay
and another option for the material is, Alabaster,
i doubt the listings accuracy...the bust in this listing has a sash and some sort of honor decoration...i am doubting it is a young Mozart.
if it is alabaster, or some sort of other stone it should be obvious..there should be a certain "mineral" sparkle to it along with some (even slight) variations in color.