Formula: Cu3AsS4

Colour: Greyish-black to black, grey/rose-brown in reflected light.

Lustre: Metallic

Hardness: 3

Specific Gravity: 4.4 – 4.5

Crystal System: Orthorhombic. Typically found as dark-grey to black massive material; crystals usually thick tabular, but may also be prismatic.

Name: From the Greek έναργής for “distinct,” referring to its cleavage.

Type Locality: San Francisco vein, Morococha District, Yauli Province, Junín – Peru

Dimorph of: Luzonite