Oxide mineralThe oxide mineral class includes those minerals in which the oxide anion (O2−) is bonded to one or more metal alloys. The hydroxide-bearing minerals are typically included in the oxide class. The minerals with complex anion groups such as the silicates, sulfates, carbonates and phosphates are classed separately.
MetasomatismMetasomatism (from the Greek μετά metá "change" and σῶμα sôma "body") is the chemical alteration of a rock by hydrothermal and other fluids. It is the replacement of one rock by another of different mineralogical and chemical composition. The minerals which compose the rocks are dissolved and new mineral formations are deposited in their place. Dissolution and deposition occur simultaneously and the rock remains solid. Synonyms of the word metasomatism are metasomatosis and metasomatic process.
Rock (geology)In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition, and the way in which it is formed. Rocks form the Earth's outer solid layer, the crust, and most of its interior, except for the liquid outer core and pockets of magma in the asthenosphere. The study of rocks involves multiple subdisciplines of geology, including petrology and mineralogy.
GemologyGemology or gemmology is the science dealing with natural and artificial gemstone materials. It is a geoscience and a branch of mineralogy. Some jewelers (and many non-jewelers) are academically trained gemologists and are qualified to identify and evaluate gems. Rudimentary education in gemology for jewellers and gemologists began in the nineteenth century, but the first qualifications were instigated after the National Association of Goldsmiths of Great Britain (NAG) set up a Gemmological Committee for this purpose in 1908.
FractureFracture is the separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the solid. If a displacement develops perpendicular to the surface, it is called a normal tensile crack or simply a crack; if a displacement develops tangentially, it is called a shear crack, slip band or dislocation. Brittle fractures occur without any apparent deformation before fracture.
AsthenosphereThe asthenosphere () is the mechanically weak and ductile region of the upper mantle of Earth. It lies below the lithosphere, at a depth between ~ below the surface, and extends as deep as . However, the lower boundary of the asthenosphere is not well defined. The asthenosphere is almost solid, but a slight amount of melting (less than 0.1% of the rock) contributes to its mechanical weakness. More extensive decompression melting of the asthenosphere takes place where it wells upwards, and this is the most important source of magma on Earth.
UlnaThe ulna or ulnal bone (: ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the wrist, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of the forearm as the little finger. It runs parallel to the radius, the other long bone in the forearm. The ulna is longer and the radius is shorter, but the radius is thicker and the ulna is thinner. Therefore, the ulna is considered to be the smaller bone of the two bones in the lower arm.
Skull fractureA skull fracture is a break in one or more of the eight bones that form the cranial portion of the skull, usually occurring as a result of blunt force trauma. If the force of the impact is excessive, the bone may fracture at or near the site of the impact and cause damage to the underlying structures within the skull such as the membranes, blood vessels, and brain.
Volcanic gasVolcanic gases are gases given off by active (or, at times, by dormant) volcanoes. These include gases trapped in cavities (vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating from lava, from volcanic craters or vents. Volcanic gases can also be emitted through groundwater heated by volcanic action. The sources of volcanic gases on Earth include: primordial and recycled constituents from the Earth's mantle, assimilated constituents from the Earth's crust, groundwater and the Earth's atmosphere.
LanthanideThe lanthanide (ˈlænθənaɪd) or lanthanoid (ˈlænθənɔɪd) series of chemical elements comprises the 15 metallic chemical elements with atomic numbers 57–71, from lanthanum through lutetium. These elements, along with the chemically similar elements scandium and yttrium, are often collectively known as the rare-earth elements or rare-earth metals. The informal chemical symbol Ln is used in general discussions of lanthanide chemistry to refer to any lanthanide.
