Term |
Definition |
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cabochan: | A style of cutting in which the top of the gemstone forms a curved convex surface. The base may be convex, concave, or flat. |
carbonaceous: | a. Referring to a rock or sediment that is rich in carbon. b. Referring to a sediment containing organic matter. |
carbonates: | Compounds in which one or more metallic or semimetallic elements combine with the carbonate radical. Calcite is the most common carbonate. |
chalky: | Having the color, luster, or general appearance of chalk. |
chemical formula: | The standard way of stating the chemical composition of a mineral in terms of the number of atoms of each element contained in that mineral. |
clastic: | Consisting of fragments of minerals, rocks, or organic structures that have been moved individually from their places of origin. Synonym detrital. |
cleavable: | Easily split into smaller fragments. See cleavage. |
cleavage: | The property of a mineral breaking along its crystallographic planes. |
color: | One of the most important properties used in determining minerals. Some minerals always show the same color, while others come in many different ones. The color of metallic (or metal-bearing) minerals is fairly constant; whereas that of non-metallic minerals is generally less so owing to the pigmentation effect of impurities. The color of a massive mineral is sometimes different from the color of its powder or streak. |
columnar: | A mineral with a structure obscurely resembling prisms, for example, hornblende. |
compact: | Dense crystalline texture requiring magnification to distinguish individual crystals or particles. |
conchoidal: | Shell-shaped; the more compact rocks, such as flint, which break with concave and convex surfaces, are said to have a conchoidal fracture. |
concretion: | A hard, compact mineral-mass of mineral matter that forms usually in sedimentary rock around a center such as bone, shell, leaf, or fossil. |
conglomerate: | Refers to a cemented clastic rock containing rounded fragments of pebble size gravel; the consolidated equivalent of gravel. The composition of rock or mineral fragments may vary widely in size, but are usually rounded and smoothed from transportation by water or wave action. |
coralloidal: | Having the form or appearance of coral. |
cryptocrystalline: | Crystalline, but so fine-grained that the individual components cannot be seen under an ordinary microscope. |
crystal: | The geometrical, faceted shape assumed naturally by minerals as they solidify, provided that nothing impedes their growth. A crystal is characterized first by its definite internal, molecular structure and second by its external form. |
crystal class: | One of the 32 possible crystallographic combinations or groups of symmetry operations that leave one point, or origin, fixed. Crystal classes are divided among the six crystal systems and deal with outward symmetry. |
crystal face: | The flat exterior surface of a crystal. |
crystal form: | The form or shape in which crystals occur, such as the cube, the octahedron, and others. |
crystal habit: | Crystal habit is a typical crystal form or a combination of forms or other shapes. It is the general shape of crystals that play an important role in identifying minerals. |
crystal system: | Minerals are classified in one or more of the six designated crystal systems, according to the geometrical shapes in which minerals crystallize. These are isometric, tetragonal, hexagonal, orthorhombic, monoclinic and triclinic. |
crystalline: | Made of crystal or resembling crystal. Crystalline rock is composed of crystals or fragments of crystals. Opposite of
amorphous. |
crystallography: | The study of crystals, including their growth, structure, physical properties, and classification by form. |
cube: | A crystal form of six equivalent and mutually perpendicular faces. |
cubic: | Having the form of a cube, as a cubic crystal. |
cubo-octahedron: | A crystal form which has faces of both the cube and the dodecahedron. |