onyx

It is composed of silica and is generated in magmatic rocks, due to the agglomeration of gases or volcanic vapor. This stone is usually black and white, although there are yellow, green and red varieties; each of which has its variants in whimsical shades and veins giving its unique, elegant and special touch. It is from slimy lustre, with opaque to translucent transparency. The crystallization system is trigonal (hexagonal variant). Its hardness is 6.5 to 7 on the mohs scale. It fractures concoidally (does not break homogeneously). it is a very tenacious and resistant mineral. It is mainly used in construction for the decoration of attention walls, screens and countertops

onyx types