After writing about quartz I think I should write about something similar, agate. Agate is a microcrystalline type of silica. It can be found in all sorts of rocks but the rocks they are in the most are volcanic and metamorphic rocks.
Agate was first discovered sometime in-between the third and fourth centuries by a Greek philosopher and naturalist named Theophrastus. Theophrastus discovered this rock by the river Achates.
Anciently it was used in the art of hardstone carving. It has been found in many ancient sites. One of these sites was mount Knossos. There it was used to illustrate Bronze Age Minoan culture.
The reason I said it was similar to quartz is because it is a type of quartz! You see agate is a formation of chalcedony which is a type of quartz. Agate is very colorful and is in all sizes.
Hope you managed to learn a fraction of a small piece of information.