To be blunt, yes. It's mostly a function of how much you need and applying heat to burn off impurities and separate out by weight. Suck out the liquid silicon layer, crystalize it, slice it. Boom, wafer.

Sand is used because of the high surface area so lower amount of heat needed to be applied, but sand is just ultimately worn down rock. Quartz for example is just pure oxidized silicon in a non-uniform crystal structure. And there's a lot of quartz. Don't like quartz? It's also in the even more common feldspar too. We as a species will run out of water before running out of silicon.

You can heat up some rocks with carbon to get silicon and CO2, then use the Czochralski method invented in 1915 to produce a single giant crystal by essentially dipping a stick into molten silicon and slowly pulling it out. Then you can slice up that big crystal into wafers.

There’s a cool photo on Wikipedia of somebody just growing a crystal: https://commons.m.wikimedia.org/wiki/File:Silicon_grown_by_C...

There’s a bit of waste, but AFAIK it’s not too bad compared to other things.

It's not the raw materials that makes semis expensive, rather it's the extensive processing it has to go through to get be transformed into the final product. The biggest issues with materials I'm aware of are often the 'conflict resources' which are in high demand but large percentages of the supply are mined in regions that for social and/or geopolitical reasons limit supply.

Yup