Malachite is a well known material and one of the most popular copper
secondary for lapidaries and jewelers alike. Note: when cutting malachite,
use water as a coolant on your wheels to remove airborne dust. Care
should be taken to wash hands before eating and to keep from breathing
cutting dust, because it contains arsenic. Reasonable precautions
will keep one safe. Malachite polishes well with tin oxide, Zam (green
rouge) and diamond. Mohs hardness is 3.5 to 4.