I am teaching about refraction, and gave out a table of refractive
indexes. A student asked about two of the entries:
fused quartz 1.458
crown glass 1.523
She wanted to know what the difference was. I wasn't exactly sure, but I
believe that crown glass is "clear" and used for eyeglasses, while fused
quartz has a greenish tint due to impurities. Is this true? I thought
crown glass was more "pure" and thus clearer. Not sure what fused quartz
is used for.