Heliotrope (mineral) Heliotrope (mineral) The mineral aggregate heliotrope (from Greek ἥλιος, "hḗlios" “Sun”, τρέπειν, "trépein" “to turn”), also known as bloodstone, is a variety of jasper or chalcedony (which is a cryptocrystalline mixture of quartz). The "classic" bloodstone is green jasper (chalcedony) with red inclusions of hematite. The red inclusions are supposed to resemble spots of blood, hence the name "bloodstone". The name "heliotrope" derives from various ancient notions about the manner in which the mineral reflects light. These are described, e.g., by Pliny the Elder ("Nat. Hist." 37.165). Heliotrope was called "stone of Babylon" by Albert the Great and he referred
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