@chu Since you said "cheapest and most abundant minerals", it made me remember being curious in the past about why some watches were advertised as having "n jewels". Turns out those are actual jewels (e.g., sapphire, ruby), used as low-friction, wear-resistant bearings for the metal shafts that pivot inside a watch movement. There are quartz movements with no jewels, so in a way they replaced the precious stones with a cheap and abundant mineral. :-)

@amenonsen @chu I worked on a few mechanical clocks at one time, and the jewels, usually rubies, were really beautiful, embedded in and among all the shiny brass clockworks. In a typical table-clock, the jewels would be a couple of millimeters or more in diameter - sort of cup-shaped to take a sharp-pointed shaft-end. In watches, I imagine they are much smaller.

@chu @CadeJohnson ❤️ I love watching watch repair videos, especially where they use a fine-tipped needle/nozzle to put a tiny drop of oil in the centre of the jewel before reinstalling the shaft.