Picture of black onyx by Shehal Joseph
Onyx occurs naturally in groups of white and black, but also is usually dyed to get the accustomed jet black color that people expect. It is a cryptocrystalline type of quartz and is chalcedony, the black form.
Black onyx is a stone for improving self-control, expelling heartache and intelligent decision making. It is meant to quiet apprehension and encapsulates too much energy as well.