Acicular malachite will effervesce in warm hydrochloric acid and antlerite will not. Atacamite is slightly softer and is usually less transparent. Brochantite is all but indistinguishable by ordinary means although its terminations are typically more rounded than the terminations of antlerite. Color is a bright emerald green or dark green to almost black. Luster is vitreous.
Crystals are transparent to translucent.
Crystal Habits include small tabular crystals and acicular or fibrous crystal aggregates that form into coatings and tufts. Also found in veins and as reniform, massive or granular specimens. Cleavage is perfect in one direction and poor in another. Fracture is uneven. Streak is pale green.