What do you know of agate? Maybe Spesfically grape agates? Their my favourite gem (^_^)
- @fearpollen
Agate and grape agate...
For agate (so the fun facts don't overlap), it's made up of a form of silica (which is also what opals are made of) called chalcedony, and a lot of the colours that show up are caused by impurities in the rock such as iron (causing red and yellow bands), and uranium (making it florescent green under certain ultraviolet light). Agates can also be made from fossils if silica replaces the organic material.
As for grape agate, it's actually not a type of agate as it doesn't have the banding and it isn't a form of chalcedony (it's structure isn't microcrystalline or cryptocrystalline, given away by the coarse texture grape agates have). In reality grape agate is just a quartz, and when it's purple it's actually a type of amethyst! And, only around 10% of grape agate are desirable for jewelry, as most grape agate is a dull grey, a brown, or is completely (or partially) colourless.
