Jasper Jasper Jasper, an aggregate of microgranular quartz and/or chalcedony and other mineral phases, is an opaque, impure variety of silica, usually red, yellow, brown or green in color; and rarely blue. The common red color is due to iron(III) inclusions. The mineral aggregate breaks with a smooth surface and is used for ornamentation or as a gemstone. It can be highly polished and is used for items such as vases, seals, and snuff boxes. The specific gravity of jasper is typically 2.5 to 2.9. A green variety with red spots, known as heliotrope (bloodstone), is one of the traditional birthstones
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