Onyx is simply Chalcedony that has bands.  It comes in just about every color. 

Sardonyx meaning:

Red onyx is Sardonyx.


Sardonyx metaphysical properties:


Sardonyx has a strong Mars energy.  Sardonyx stones are great for start-ups, needed confrontations, clear-sighted vision, inspiring followers, improving vision, taking the lead, winning competitive sports, bold moves, inciting action, courageous strategy, and attracting these qualities to yourself in the forms of opportunities and men.