ATM Is fused quartz green?

[pete.koziar@baltsun.com]

A week or so ago, I caused a flurry of responses on identifying whether a piece
of glass I have is quartz or pyrex. My original question dealt with specific
gravity, and, after filtering through all the responses, the answer seems to be,
"maybe yes--maybe no." The best idea I got dealt with the UV absorbency of the
glass. Pyrex heats up in the sun, quartz doesn't.

Here's a simpler question. The piece I have is slightly green on the edge. To
me, this says it's pyrex, but I've never seen a piece of fused quartz glass.
It's circular, about .75" thick and 5" in diameter. 

It looks like it's of mirror quality and not lens quality. When I rotate the
glass, looking through it what I see seems to "swim" slightly which says it's
got internal variations (stirations? striations? whatever). The surface seems
flat and glossy but I'm not sure if it's been polished or not.

Is fused quartz greenish like pyrex (or plate), crystal clear like crown,
greyish like flint, or something else? (I'm talking "Glass identification for
Dummies" here ;)

                                    - Pete Koziar