This is a Chrome Diopside cluster from the Merelani Hills in the Arusha region of Tanzania. It is a calcium silicate based mineral that gets it's green color from the chromium inclusions in it.
This piece has awesome terminations with all the main tips being almost damage free. The piece is secured to an acrylic base using mineral putty.
This piece measures ~3.5cm x 2.8cm x 2cm. The acrylic base measures 3.1cm x 3.1cm.