What is quartzite, and how does it differ from beach sand?	Quartzite is a metamorphic rock of near-pure SiO₂ formed by pressure-cooking sandstone for hundreds of millions of years; beach sand is a mix of iron, organic salts, and shell fragments — chemically unusable for chips.
What is the chemical formula of quartz?	SiO₂ — silicon dioxide, two oxygens bonded to one silicon in a tetrahedral lattice.
What is the Mohs hardness of quartz?	7 — hard enough that the chapter calls it “harder than steel.”
What purity does high-grade quartzite reach straight from the mine?	99.86% SiO₂.
What purity is required for chip-grade silicon?	99.9999999% — nine nines, or 9N.
Name three impurity species that can ruin silicon’s electrical properties.	Boron, phosphorus, and iron (also: aluminum, calcium — any three from the chapter’s list).
Which country is the largest producer of raw silica?	China.
What role does Spruce Pine quartz play in chipmaking specifically?	It supplies the world’s purest natural quartz used to make the crucibles in which polysilicon is melted during crystal growth.
Why is silicon’s stubbornness (chemical inertness) both an asset and a challenge?	It is an asset because the crystal survives eons without breaking down; it is a challenge because extracting silicon from SiO₂ is correspondingly difficult — the same bond that resists nature resists the smelter.
What does the chapter identify as the first myth to dispatch about chip materials?	That semiconductors are made from beach sand — they are not; beach sand is too contaminated.