I think the author is using 'silica' and 'silicon' interchangeably in the fifth and sixth paragraphs, ie: > boron or phosphorus, could be added to the molten s

I think the author is using 'silica' and 'silicon' interchangeably in the fifth and sixth paragraphs, ie: > boron or phosphorus, could be added to the molten silica in precise amounts to change the silica’s carrier concentration. Depending on what dopants he added, the silica turned into p-type or n-type silicon In almost every case the author probably means silicon since this is a method used for growing semiconductor crystals, not quartz crystals.