An assortment of the quartz family, Black onyx is a famous, normal and monetarily reasonable gemstone. The mohs scale rates this wonderful black stone at 7 in terms of its hardness. Even though black onyx is known for its profound dark shading, it might show groups of white. Sardonyx is a type of onyx which differs in shading from white, to red or reddish brown. US, Brazil, India, Pakistan and Madagascar are the places where black onyx can is usually found. It is the Zodiac stone for Capricorns.