Quartz, though, is at least a partial exception to this rule. ... like flint. Chemically, quartz is nearly pure silicon dioxide (SiO 2). When there are no impurities, ...

It’s important to note that the “flint rock” you find is unlikely to be actual flint or a rock — it’ll probably be some other hard mineral, such as quartz, chert, or agate.

When Jonathan Quarles founded the BTL Group, a Detroit-based international business development consultancy and investment firm, he didn’t intend to get into the business of water. But in 2018 ...