Approximately 5g each stone.
Onyx primarily refers to the parallel banded variety of the silicate mineral chalcedony. Agate and onyx are both varieties of layered chalcedony that differ only in the form of the bands: agate has curved bands and onyx has parallel bands. The colours of its bands range from black to almost every colour.
Onyx is said to impart personal strength. A destiny stone that will allow you to look to the future. May promote stamina and self-confidence.