Peridot

Gem of only green color, but going from yellow green to intense green with a strong birefringence.
Exploited for more than 3000 years in Egypt on the island of Zabargad.
Also called Olivine in mineralogy.
Very appreciated in the Middle Ages, it was also the most appreciated stone of the Baroque period.
The main deposits are currently found in China, Pakistan and Burma, but also in the United States and Brazil.