Thanks, Having caught quite a number of this type I was always on the lookout for a spectrum of one. They have definite mechanical/fragmentation properties and I was hoping it would be somehow different it spectroscopic composition. Maybe very high or very low in some element but it doesn’t seem so with what I have here. The other possibility is that there are some IR features (which I didn’t get with this example) that may show the differences. perhaps very strong O and H lines indicating the possibility some ice content….
However, it is yet another example of the power of this technique that we can even ask these questions!
Clear skies and all the best for 2019
PS will you be attending the astrofest in February? perhaps we can meet for a drink.