Clinozoisite is a variety of stone that is often found opaque and of poor quality.
The transparent quality, called "gem", is very rare and appreciated by collectors.
Clinozoisite has a chemical composition close to that of the Epidote, that is why some minerals being as much of the Epidote as of the Clinozoisite is called Clinozoisite-Epidote.
To learn more about Clinozoisite, see Mindat.org->