This is a beautiful specimen of small blue-green dioptase crystals from the Malaquita Mine in Sonora, Mexico. The Malaquita Mine is most known for producing malachite, chrysocolla, quartz and goethite, however some spots of the mine produce small dioptase crystals that are most commonly found on quartz.
Dioptase is an uncommon mineral found mostly in desert regions where it forms as a secondary mineral in the oxidized zone of copper sulfide mineral deposits. This copper based mineral forms small rhombohedral crystals, typically less than 0.75 cm in length.
It is popular with mineral collectors due to it's vibrant color and it is occasionally cut into small emerald-like gems.