Subject: Are diatoms used to make glass and are they in the silica gel packets?

I Know that diatoms have cell walls (shells) made of silica, a glassy 
substance.  I also know that sand can be used to make glass. But can one then 
conclude that diatoms are used to make glass?  I can't find a website that 
addresses this.  Alos, my students want to know if diatoms are in the silica 
gel packs when they buy new shoes or is the silica from something else.   
Thanks a million on behalf of my seventh graders!

Re: Are diatoms used to make glass and are they in the silica gel packets?