Amazonite - Wikipedia
https://en.m.wikipedia.org/wiki/Amazonite
Amazonite, also known as Amazonstone, is a green tectosilicate mineral, a variety of the potassium feldspar called microcline. Its chemical formula is KAlSi 3 O 8, which is polymorphic to orthoclase.. Its name is taken from that of the Amazon River, from which green stones were formerly obtained, though it is unknown whether those stones were amazonite. ...