This dioptase crystal is quite large for a single, with the trademark bright and unique color.  This is a great crystal collectors piece.
 
Dioptase is a strikingly vibrant mineral known for its deep emerald to bluish-green color, prized by collectors for its powerful displays of color. It is a secondary copper mineral, forming prismatic, vitreous crystals typically found in oxidized copper deposits. With a relatively low Mohs hardness of 5, dioptase is too fragile for most jewelry and is usually only available as raw crystals. Significant deposits are found in arid, copper-rich regions like Kazakhstan, Namibia, and the Democratic Republic of Congo.
 
From Mindouli, the Congo Republic.  Shown on 1" x 1" acrylic base and mounting putty, included with purchase.