ATM ash tray mirror

[bj712@scn.org (Mark Zemanek)]

Last weekend I went to a yard sale where there was plenty of glass for 
sale, and purchased an ash tray with a 5" diameter and a 1.25" thick 
base. It looks to be made of high quality lead crystal. It has a concave 
base with somebody's initials etched into it. Probably manufactured in 
the 1960's-70's.

I also bought several glass furniture glides which are 1/2" thick...one 
three inch, and three four inch. These pieces are probably from the 
1930's or 1940's. They're stamped with the mark *HA*, the manufacturer 
being Hazel Atlas (I believe Anchor Hocking's competitor in those days). 

I'm wondering if any of this glass can possibly be used to make mirrors. 
Just figured I'd ask here first before finding out the "hard" way. If so, 
I'm considering using the 5" to make a planetary scope in a focal range 
that I can leave spherical, and using the 4" blanks to hone my 
parabolical figuring skills. All comments are highly appreciated...

Mark Zemanek
Seattle,Washington