central heating - a heating system in which air or water is heated at a central furnace and sent through the building via vents or pipes and radiators
exists and is an alternate of . Five physical characteristics of a mineral are: hardness, luster, diaphaneity, colour, and streak.
Igneous rocks have many distinct characteristics. For example, light-colored igneous rocks are more acidic, and have over 65% silica. Dark-colored rocks are more basic and have a higher percentage of ferro-magnesian minerals. Igneous rocks are broken up in to three main groups: acid, intermediate, and basic. Acid rocks have over 65% silica, intermediate rocks have 55-65% silica, and basic rocks have 45-55% silica.