[L,. metallum.] Minerals having certain properties, the chief of which are - 1. They are a:l opaque, and they all have a shiny surface known as the metallic lustre. 2. They are good conductors of heat and electricity. 3. With the exception of gold and copper, their color is a grayish white. 4. With the exception of mercury, they are all solids at ordinary temperatures. 5. All metals can be melted, but the temperatures at which they assume the fluid form vary very much. 6. Great weight, most metals being heavier than water. Platinum is more than twenty times as heavy as water. Metals differ from each other in malleability, ductility, and tenacity. A metal is said to be malleable when it can be hammered out into thin sheets. Gold is the most malleable, and next to it in order are silver, copper, platinum, iron, tin, zinc, and lead. Some metals are so brittle that they cannot be hammered at all. When a metal can be drawn out like wire, it is ductile. Gold is the most ductile of all metals. When a metal has the power of holding together under a strain, it is said to have tenacity. Iron is the most tenacious or elastic of all metals.