Sapphire

How easyis it to make clear glass that blocks the appropriate frequencies? Sappire and Quartz each have excellent properties though some difficultly in preparation. I don't know about a glass of Calcium, Silicon, Magnesium and Aluminum oxides. How difficult is it to get all coloring agents out like Manganese and Iron?
Thanks

"Combs, Mike" wrote: Are we discussing sapphire because there's a perception that glass is not up to the job? My understanding was that one of the early surprises of the first High Frontier work was the calculation that ordinary glass panels set in a metal framework could be used even in habitats with aradius of curvature of several miles. Glass is certainly going to be much cheaper than many alternatives we might speculate on, and I think theexpense is going to be a major factor considering that we're talking about square miles of it. Glass will be easy to make from lunar or asteroidal materials.
Regards, Mike Combs