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
Non-metallic inclusions During deformation, which occurs from flatting, forging, and stamping, non-metallic inclusions can cause cracks and fatigue failure in steel. When investigating the influence of non-metallic inclusions on the quality of steel, of great importance are the properties of these inclusions: size, shape, chemical and physical characteristics. All these properties depend on the chemical composition of steel, method of smelting and for certain steel grade. These properties can change within wide limits even within the same mode of production. Different methods for analysis of non-metallic inclusions have been developed and are now in use. These make it possible to determine content,