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.
MINERALS. Rocks are made of natural, nonliving chemical substances called minerals. Some rocks contain only one mineral. For example, marble is made of the white mineral calcite. Most rocks, however, contain CRYSTALS of several different minerals.