Framebuilders - Identifying Chromoly vs. HiTensil

I am looking at an older bike and would like to know if there is a way to identify if the frame is Chromoly or HiTen steel. It is a GT Dyno Moto 7. There is not much info about these, besides 2 or 3 people that have posted theirs online. No stickers to indicate frame material.

Isn't that bike one of those curvy tubed town bikes? If so, I seriously doubt it's 4130 since that would be overkill for a bike like that, plus the high strength tubes are harder to bend which would increase cost.

educate me on why this is important to you?

I am looking at an older bike and would like to know if there is a way to identify if the frame is Chromoly or HiTen steel. It is a GT Dyno Moto 7. There is not much info about these, besides 2 or 3 people that have posted theirs online. No stickers to indicate frame material.
If you can grind some of it, the sparks might indicate something: http://www.capeforge.com/Spark%20testing.html

Weight of the frame would be the big tip-off, also any visible tubing should be @ 1mm thick to .6mm thick on 4130. If a bike is designed to the same load specs in non chromo, it will have a wall thickness about twice that thick, of course they may not bother since the bike would not be expected to bear the same kind of loads. The fact there aren't sticker doesn't mean much, as you know there is a whole straight wall tubing option and a no-name straight wall tubing option in chromo, below the marqui tube sets that rate a sticker.

Thanks for the replies.
-It probably is not Chromoly based upon use of the bike.
-Weighing the frame would be the most realistic in determining the frame material if it wasnt' 1500 miles away from me. Spark test is a good idea but the bike has a nice paint job.
-Important to me so I know what I have. Useful probably not.

Here is the bike in question. The owner emailed GT/Schwinn and they have no records.
http://i103.photobucket.com/albums/m130/ratrodbikes/Dyno/dyno2-2.jpg