bearing in mind comments about nominal fee cost, is it worth considering that this is simply some ultra cheap type of bottle glass with masses of inclusions which are usually described as 'seeds or stones' and quite often this whitish/grey colour. Such low grade glass is frequently this greenish colour owing to the iron impurities in the sand and with non-silica debris that doesn't melt at the same temp. as the sand. This 'bottle' type glass would probably also be more inclined to contain bubbles than refined glass. Just a thought.
Might see if you can scratch your name on a window pane to test the hardness of this material - quartz should be 7 on the Mohs scale, I think.
Of course if you really want to determine the nature of the inclusions then break the obelisk and take some of the whitish 'crumbs' to another chemist.