QUARTZ CRYSTAL COVERED BY SMALL SIDERITE CRYSTALS. TRANSPARENT CRYSTAL AT THE TOP AND MILKY AT THE BASE. PIECE FROM THE PANASQUEIRA
Quartz is the most common mineral, the most abundant that can be found on earth.
It is composed of silicon and oxygen with the formula SiO₂.
According to the Nickel-Strunz classification, quartz belongs to the class
