Sahara sand is not suitable for construction or island building because it is too spherical, desirable sand is jagged because it clumps together better.
> Wonder why this isn't working out as the "new construction technique" hit success that it seems, with a little optimisation, it could be?
Well, it's incredibly dangerous to set up an array of solar concentrating fresnel lenses and/or mirrors anywhere near human beings. Concentrating radiation on things which are becoming more and more shiny and/or refractive as you go can go very wrong, as you start having to manage the caustics of even the cloudy glass you end up making.
