Chalcedony to as prase. However, the term prase is also used to describe green quartz, and to a certain extent is a color-descriptor, rather than a rigorously defined mineral variety.) Blue-colored chalcedony is sometimes referred to as "blue chrysoprase" if the color is sufficiently rich, though it derives its color from the presence of copper and is largely unrelated to nickel-bearing chrysoprase. Heliotrope is a green variety of chalcedony, containing red inclusions of iron oxide that resemble drops of blood, giving heliotrope its alternative name of bloodstone. In a similar variety, the spots are yellow instead, known as plasma. Moss agate
Aluminium alloy inclusions Aluminium alloy inclusions An inclusion is a solid particle in liquid aluminium alloy. It is usually non-metallic and can be of different nature depending on its source. Inclusions can create problems in the casting when they are large and in too high concentration. Here are examples of problems related to inclusions: In contact with ambient air, liquid aluminium reacts with the oxygen and form an oxide film layer (gamma-AlO). This layer becomes thicker with time. When aluminium is moved, this oxide film gets mixed inside the melt. In primary aluminium production, aluminium carbides (AlC) originates from the reduction of alumina