Precious gems that go in jewelry have to be harder than a 7 on the Mohs scale due to quartz being the hardest airborne mineral and would scratch them, so does that mean we breathe in quartz on the daily and our lungs don’t mind?
Unless you are by a nearby volcanic eruption, there just aren’t natural processes which make silica grains fine enough for you to breathe in and be dangerous. Obviously it’s not good if you breathe in sand sized particles of silica either, but much these would typically get stuck in your mouth or throat before making it to your lungs. Also, it’s easy to see when there is a sandstorm and take appropriate measures, ie. stay inside or [wrap up](https://i.imgur.com/ASPXRMq.jpg).
It’s pretty much just a industrial settings where very fine silica particles are a hazard, and those places *should* be giving their workers appropriate safety wear.
One of the reasons why certain asbestos minerals are a hazard is because they can easily break apart into very fine fibres, just through regular handling without any industrial process. Exposure to certain asbestiform mineral fibres has been linked to lung cancer, similar to the dangers described in the article you linked.
ELI5: Gemstones scratch. The harder ones resist scratching longer. If you scrape your soft stone on a harder thing it will scratch. Those things that scratch your gemstone? You don’t want to breathe them. Door knobs are hard to inhale for most of us. /end
I am genuinely curious where you got this information regarding gems having to be harder than a 7 on the mohs scale for jewelry due to airborne silica.
I have always understood “Precious gems” to designated upon fabricated “rarity”, not hardness. Those gems that go in rings are typically harder because of day to day wear that occurs every time that you do anything with the ring on. Dishes, pockets, keys etc.
I’m certain you know this, however, I just want to point out that many many materials can be used as the gemstone under 7 mohs for jewelry. Including very soft materials such as bone, coral, shell, etc.
Others gave you a better response regarding silica.
Quartz is made of silica, and crystalline silica [is really bad for people to breathe](https://www.cancer.gov/about-cancer/causes-prevention/risk/substances/crystalline-silica) _if breathed in high enough amounts_ (that means high concentrations and for a long time each shift, specifically) . You’re unlikely to encounter truly dangerous amounts of airborne crystalline silica outside of an industrial setting, and even then the hazards are known and understood. Any legitimate place that uses crystalline-silica containing materials will have protection mechanisms for their workers.
To sum up: crystalline silica is bad for you, and your lungs certainly _do_ mind, but it’s likely not a big deal.