epidote
noun
ep·i·dote ˈe-pə-ˌdōt 
: a yellowish-green mineral Ca2(Al,Fe)3Si3O12OH usually occurring in grains or columnar masses and sometimes used as a gemstone
Example Sentences
Recent Examples on the Web Specifically, the multi-heavy mineral prospect consists of abrasives garne and epidote, and zircon, magnetite and gold. 
Elwood Brehmer, Anchorage Daily News, 7 Nov. 2019 That’s the iron silicate minerals epidote and chlorite. Peter Hessler, National Geographic, 25 July 2016
Elwood Brehmer, Anchorage Daily News, 7 Nov. 2019 That’s the iron silicate minerals epidote and chlorite. Peter Hessler, National Geographic, 25 July 2016 Word History
Etymology
French épidote, from Greek epididonai to give in addition, from epi- + didonai to give — more at date
First Known Use
1808, in the meaning defined above