• A mineral found in northern Ireland and elsewhere, having the formula 5CaO • 6SiO2 • 5H2O.
  • Ca:4H O, the artificial product tobermorite, G, of Brunauer, a hydrated calcium silicate having CaO/SiO ratio in the range 1.39 to 1.75. It forms minute layered crystals that constitute the principal cementing medium in Portland cement concrete, a mineral with 5 mols of lime to 6 mols of silica, usually occurring in plate-like crystals that are easily synthesized at steam pressures of about 100 psi and higher. Tobermorite is the binder in several properly autoclaved products.