#MinCup26 It's the time for QUARTZ! A speciality of our planet in a mostly quartz-free cosmos.

This mineral can do anything: a gem in lots of colours, a geothermometer, geological strain gauge, a trap for geofluid samples, and much more.

Here is a beautiful stormy seascape in this cut and polished Scottish agate - all due to the microtextural subtlety and complexity of quartz.