Basalt is a grey volcanic rock, known and used since the Roman era, excavated in the Bagnoregio area of Viterbo, near Lake Bolsena. Characterised by a compact and even structure, it has excellent physical-mechanical frost and wear compression resistance properties. A stone with a substantially even iron grey porous base, with frequent millimetre-sized white crystals scattered in the base mass. Pitted holes, generally millimetre in size, are often elongated and arranged to grant material a definite direction. Its noble and neutral colour matches all modern and non-modern materials like steel, wood, glass and aluminium, enhancing their beauty and use.