Many beautiful specimens of malachite contain special combinations with other minerals, such as the azure blue of azurite , the baby blue of chrysocolla , or the rusty red of limonite . Luster is dull in massive forms and silky as crystals. Transparency is opaque in massive form and translucent in crystalline forms. Crystals are acicular or fibrous and form in tufts and encrustations. Cleavage is good in one direction but rarely seen.
Fracture is conchoidal to splintery.
Streak is green. Associated Minerals include limonite , chalcopyrite , native copper , calcite , cuprite , azurite , chrysocolla , and other copper deposit minerals. Best Field Indicators are color banding and reaction to acid.