One of our favourite external and swimming pool materials – highly contemporary and very slip resistant. Twilight Basalt is a dark grey to black basalt with Class 5 wear resistance (suitable for all commercial and domestic projects). Twilight Basalt is available with two types of swimming pool surrounds as well as treads and risers from quarry making it an economical and safe basalt for swimming Pool and staircases. Unlike other basalts, Twilight Basalt contains lime and must be cleaned with an acid-free product such as our Detertwins cleaner. Fine pencil fissures can appear shortly after laying Twilight basalt. These veins are a normal natural occurrence.