What sort of rock is this one?
If the second picture is under a black light, its most definite an indiction that the minerial is fluorite which fluoresce blue and violet. This and the moh hardness test should tell you more. Remember that a steel file has a hardness of 6.5 and fluorite a 4 so the file will scratch the mineral but not the other way. I believe that fluorite has a slight double defraction as well but this isnt always a good indicator since some amythest can appear cloudy. The hardness test should tell you.