Definitions Pertaining to Stones
| ACIDIC ROCK | A type of igneous rock (e.g. granite) that consists predominantly of light-colored minerals and more than 66% free or combined silica. (1) |
| ALKALINE ROCK | A rock containing more than average amounts of potassium- and sodium-bearing minerals. (1) |
| AMORPHOUS | Literally, "without form"; applied to rocks and minerals that lack definite crystal structure. (1) |
| AMPHIBOLES | A group of closely related, dark-colored rock-forming silicate minerals. (1) |
| AMYGALOIDAL ROCK | A volcanic rock containing numerous gas cavities (amygdules) filled with such secondary minerals as calcite, quartz, and zeolites. (1) |
| AMYGDULE | A mineral-filled cavity formed in an igneous rock by escaping gas. (1) |
| APHANITIC ROCK | A rock in which the crystalline constituents are too small to be distinguished with the unaided eye. (1) |
| ARGILLACEOUS | Containing or composed largely of clay. (1) |
| ARSENATES | Minerals in which the arsenate radical (AsO4) is an important constituent. (1) |
| BORATES | A group of minerals in which the borate radical (BO3) is an important constituent. (1) |
| BOTRYOIDAL | Resembling a bunch of grapes; describes hematite and a number of other minerals in which very small radiating crystals are arranged in massive clumps, giving a surface covered with spherical bulges. (1) |
| CALCAREOUS | Containing calcium carbonate or calcite. (1) |
| CARBONACEOUS | Composed largely of organic carbon (i.e., carbon derived from plant and animal tissue). (1) |
| CABOCHON | A cut and polished stone, round, oval or square-shaped with one "rough" edge. Cabochons are often used in jewelry. (2) |
| CATACLASTIC ROCK | A metamorphic rock produced by the crushing and grinding of preexisting rocks, which are still bisible as crushed and flattened minerals and as angular fragments. (1) |
| CHATOYANCY | The property, found in many stones, of showing movement, illumination or opalescence within the stone itself. Tiger's-eye, cat's-eye, moonstone, sunstone and many others exhibit this phenomenon. (2) |
| CLEVAGE | The tendency of some minerals to break along one or more regular, smooth surfaces. (1) |
| CONCRETION | An accumulation of mineral matter, formed when particles of silica, pyrite, gypsum, etc. become cemented together into an orderly, rounded, often artificial-looking form. (1) |
| CONTACT METAMORPHISM | Metamorphism directly related to the intrusion of magmas and taking place at or near the contact with the molten rock. (1) |
| CRYSTAL | A solid mass of mineral, having a regular geometric shape and bounded by smooth, flat surfaces (crystal faces). (1) Natures' three-dimensional geometric forms whose outward appearance mirros the internalized perfect ordering of atoms. The unity among the particles comprising crystals vibrate with a cosmic harmony which can be tapped into and used in healing or in the evolution of consciousness. Crystals are capable of reflecting pure light and color that can be channeled in numerous ways. (3) |
| CRYSTAL HABIT | The actual form of a crystal; determined by the shape and relative proportions of the crystal faces. (1) |
| CRYSTAL SYMMETRY | The repeat pattern of crystal faces, caused by the ordered internal arrangements of a mineral's atoms. (1) |
| DETRITAL SEDIMENT | A deposit of mineral and rock fragments that have been transported to their place of deposition. (1) |
| DIFFERENTIATION | A process by which different types of igneous rocks are derived from the same parent magma. (1) |
| DISCORDANT | Describes an intrusive igneous body whose margins cut across the bedding (or foliation) of the surrounding rocks. (1) |
| DYNOTHERMAL METAMORPHISM | Metamorphism resulting from the combined effects of heat and pressure; also called regional metamorphism. (1) |
| ELECTRUM | The product of blending various metals, such as gold and silver. Rarely found in nature, electrum has a long magical history. (2) |
| EPITHERMAL VEIN | A vein formed at shallow depths from ascending hot solutions. (1) |
| EQUIGRANULAR ROCK | A rock whose mineral particles are of the same general size. (1) |
| ESSENTIAL MINERALS | The mineral constituents of a rock (usually an igneous rock) that are used to classify and name the rock. (1) |
| EXTRUSIVE ROCK | An igneous rock that solidifies on the surface of the earth. (1) |
| FELDSPAR | A group of abundant rock-foming silicate minerals, including orthoclase and microcline (potash feldspars) and albite, oligoclase, andesine, labradorite, bytownite, and anorthite (the plagioclase, or soda-lime, feldspars). (1) |
| FELDSPATHIC ROCK | A rock that contains feldspar as a principal constituent. (1) |
| FELDSPATHOIDS | A group of minerals (e.g. leucite, nepheline, and sodalite) that are similar in composition to the feldspars, but contain less silica. (1) |
| FERRUGINOUS | Containing iron. (1) |
| FLOW BANDING | A structure (in some volcanic rocks) consisting of alternating layers of unlike mineralogical composition and formed as a result of flowing lava. (1) |
| FOLIATION | The laminated structurepresent in regionally metamorphosed rocks that results from segregation of different minerals into roughly parallel layers. (1) |
| FRAGMENTAL ROCK | Sedimentary rock consisting of rock and mineral fragments. (1) |
| FRIABLE | Easily crumbled or pulverized. (1) |
| FUSION | The process of being melted or dissolved by heat. (1) |
| GNEISSOSE ROCK | A rock that has the banded appearance of a gneiss but is not formed by metamorphism. (1) |
| GRANULOSE | A metamorphic texture characterized by granular minerals, such as quartz, feldspars, and garnet, in alternating streaks and bands. (1) |
| HALIDES | A group of minerals that are primarily compounds of the halogen elements bromine, chlorine, fluorine and iodine. (1) |
| HARDNESS | Resistance of a mineral to abrasion or scratching. (1) |
| HEALING STONES | Any natural precious or semi-precious stones, rocks or crystals whose healing properties are known and used to balance, restore or maintain physical, mental, emotional or spiritual wellness. (3) |
| HYDROTHERMAL ALTERATION | An alteration of minerals or rocks by the action of superheated mineral-rich fluids, usually water that has been heated to very high temperatures within a crystallizing magma. (1) |
| HYDROTHERMAL METAMORPHISM | Changes in the structure or composition of rock, caused by the action of hydrothermal fluids. (1) |
| HYDROTHERMAL REPLACEMENT | A change in a rock or mineral deposit due to the addition or removal of minerals by hydrothermal fluids. (1) |
| HYPOTHERMAL VEIN | A vein formed at relatively great depth and at relative high temperatures (330~-500~C.) (1) |
| IGNEOUS ROCK | Rock formed by the solidification of magma. (1) |
| INTERMEDIATE ROCK | Igneous rock (e.g. syenite or diorite) that is transitional between acidic and basic rock, having a silica content of between 54% and 65%. (1) |
| INTRUSIVE ROCK | An igneous rock that formed underground, from magma that was squeezed into cracks or crevices, or between layers of older rocks. (1) |
| "JAPANESE" TWINS | Simple contact twins (in quartz) in which two single crystals, usually broad flattened prisms, are joined in the same plane at an angle of about 84~. (1) |
| LACCOLITH | A lens-shaped body of igneous rock with a dome-shaped upper surface and a flat bottom surface, and with both surfaces parallel to the bedding or foliation of the enclosing rocks. (1) |
| LAMELLAR | Composed of thin layers, plates, or scales. (1) |
| LAMINATED ROCKS | Sedimentary rocks that are formed of numerous very thin layers.(1) |
| LAVA | Molten rock material extruded onto the surface of the earth. (1) |
| LAVA FLOW | A body of rock formed by a single outpouring of lava. (1) |
| LENTICULAR | Lens-shaped. (1) |
| LOPOLITH | A large, lenticular, centrally sunken mass of igneous rock whose surfaces are concordant with the enclosing rocks. (1) |
| LUSTER | The surface appearance of a substance, or the manner in which it reflects light. (1) |
| MAGMA | Molten rock material, beneath the solid crust of the earth, that solidifies to form igneous rocks at or below the earth's surface. (1) |
| MAGMATISM | Any process by which magma solidifies into volcanic or plutonic rock. (1) |
| MATRIX | The fine-grained material (groundmass) that surrounds the larger crystals or particles in a porphyritic or sedimentary rock. Also, any material, such as clay or rock, in which a crystal, fossil, etc. is embedded. (1) |
| MESOTHERMAL VEIN | A vein that forms at intermediated depth and temperature (1) |
| METAMORPHIC ROCK | Any rock (e.g. schist, gneiss, etc.) that was formed in some fashion from a pre-existing rock, through heat, pressure, the effect of superheated fluids, or any combination of these forces. (1) |
| MICA | A group of soft silicate minerals (e.g. biotite, muscovite) that have perfect basal cleavage in one direction and can easily be split into characteristic thin, elastic, pearly sheets. (1) |
| MICROCRYSTALLINE ROCK | A rock whose crystals are too small to bee seen without a microscope. (1) |
| MINERALS | The natural chemical elements or compounds that occur in nature and form the earth's crust. (3) |
| MINERAL ENVIRONMENT | The rock (or rock type) in which a mineral or a group of associated minerals forms and occurs. Mineral environments include igneous, sedimentary, and metamorphic rocks, as well as several types of veins and replacement deposits. |
| MINERAL STABILITY | The ability of a mineral to remain unaltered over a stated range of pressure and temperature. (1) |
| MOLYBDATES | A group of minerals (e.g. wulfenite) in which the molybdate radical (MoO4) is an important constituent. (1) |
| NODULAR | Having the shape of or composed of irregular lumps of rock or mineral. (1) |
| ORGANIC COMPOUNDS | Compounds produced in or by plants and animals and containing carbon as the essential ingredient. (1) |
| OUTCROP | A mass of bedrock that is exposed at the surface of the earth. (1) |
| OXIDES | A group of minerals in which oxygen, combined with a metal, is a major constituent. (1) |
| OXIDIZED ZONE | The part of an ore body (usually the upper part) that has been altered by donward percolating groundwater, containing disolved oxygen and carbon dioxide. (1) |
| PARTING | The tendency of some minerals to separate along certain planes, which are not related to the crystal symmetry of the mineral; usually due to twinning or deformation. (1) |
| PEGMATITE | An igneous rock of extremely coarse grain size. Usually found as dikes within a larger putonic or metamorphic rock mass, pegmatites are often excellent sources of large, fine crystals, especially of quartz, tourmaline, feldspar, and mica. (1) |
| PERROGRAPHY | The branch of geology that deals with the description and classification of rocks. (1) |
| PETROLOGY | The study of rocks, specifically their composition, origin, and modes of occurrence. (1) |
| PHANERITIC ROCK | An igneous rock in which all of the essential minerals can be distinguished with the unaided eye. (1) |
| PHENOCRYST | A prominent crystal (in a porphyritic rock) surrounded by smaller mineral grains. (1) |
| PHOSPATES | A group of minerals (e.g. apatite) in which the phospate radical (PO4) is an important constituent. (1) |
| MASSIVE MINERAL | A mineral that occurs either without any definite external crystal form or in poorly defined masses of small crystals. (1) |
| PIPE | A vertical, cylindrical mass of igneous rock. (1) |
| PISOLITIC | Consisting of rounded grains like peas or beans. (1) |
| PLACER | A deposit of heavy mineral particles (e.g. gold) that have weathered out of the bedrock and been concentrated mechanically, usually by the action of streams. (1) |
| PLUG | The solidified core of an extinct volcano. (1) |
| PLUTON | Any deep, intrusive igneous body, of any size, whose exact form has not been determined. (1) |
| PLUTONIC ROCK | A granular igneous rock that has solidified at great depth and shows distinct grain texture (e.g. granite). (1) |
| PORPHYRITIC ROCK | An igneous rock in which larger crystals (phenocrysts) are enclosed in a fine-grained groundmass, which may be crystalline or glassy. (1) |
| PRECIOUS STONES | Multi-colored crystalline gem-stones that usually display transparency and are capable of reflecting high amounts of light and pure rays of color; stones best used when trying to affect or heal the subtle bodies; rubies, emeralds, diamonds, sapphires, aquamarine, topaz etc. (3) |
| PRECIPITATION | The process by which a suspended or dissolved solid is separated out or a liquid. (1) |
| PSEUDOMORPH | A mineral that has taken the outward crystal form of a different mineral. (1) |
| PYROELECTRICITY | An electric charge produced in a crystal by heat. (1) |
| PYROXENES | A group of closely related, dark-colored rock-forming minerals (e.g. augite, diopside, and acmite). (1) |
| RADIATED | A process by which crystals are exposed to intense amounts of x-rays which alters the molecular structure and changes the natural form of color; clear quartz crystals radiated to exemplify smoky quartz. (3) |
| RADICAL | A group of exygen atoms clustered about a nonmetallic atom (e.g. silicon, phosphorus, sulfur) so as to form a "structural unit" that behaves like a single atom. (1) |
| REPLACEMENT | A process by which one mineral replaces another, while often retaining the physical form of the first mineral. (1) |
| SECONDARY MINERALS | Minerals that are formed by the alteration of preexisting (primary) minerals. (1) |
| SEDIMENTARY ROCK | A layered rock, formed through the accumulation and solidification of sediments, which may originally be made up of minerals, rock debris, or animal or vegetable matter. (1) |
| SEMI-PRECIOUS STONES | Any number of multi-colored stones, usually dull opaque and nontransparent; stones reflecting colors and energies that are best used when trying to affect or heal physical, subconscious or emotional imbalances; turquoise, lapis, agate, malachite, etc. (3) |
| SILICA | Silicon dioxide (SiO2), a tremendously abundant mineral that occurs widely and in many forms, including quartz, chalcedony, opal, and chert. (1) |
| SILICATES | A group of minerals (e.g. quartz and orthoclase) composed essentially of SiO4 tetrahedra in different arrangements. (1) |
| SILL | A tabular, sheetlike body of intrusive igneous rock, which has been injected between layers of sedimentary or metamorphic rock. (1) |
| SLATY CLEAVAGE | A variety of foliation typical of slates and characterized by parallel arrangements of clay minerals. (1) |
| STOCK | A small, irregularly shaped body of intrusive igneous rock with a surface area of less than 65 square kilometers. (1) |
| STREAK | The color of the powder of a mineral produced by rubbing the mineral over the surface of a piece of unglazed, white porcelain. (1) |
| STRIATIONS | Minute parallel grooves or narrow channels on crystal faces. (1) Fine grooves or lines which are found on certain stones, such as kunzite. (2) |
| STRUCTURE | Large features of rock masses, such as flow banding and bedding; in minerals, structure refers to the shapes and forms of crystal groups and masses. (1) |
| SULFATES | A group of minerals (e.g. gypsum and barite) in which the sulfate radical (SO4) is an important constituent. (1) |
| SULFIDES | A group of minerals (e.g. pyrite, galena, and sphalerite) in which sulfer is in combination with one or more metals (copper, iron, or zinc). (1) |
| SULFOSALTS | A group of minerals in which sulfur combines with the semi-metals (arsenic, antimony, and bismuth) to form what are called negative ions, which then combine with the metals (lead, silver, copper, and zinc) to form such minerals as enargite, tetrahedrite, and pyrargyrite. (1) |
| TENACITY | The ability of a substance to resist separation. (1) |
| TERMINATE, TERMINATED | To come to a point; to reach completion at the apex; when the faces of a crystal meet together to form the top peak. (3) |
| TEXTURE | The surface apppearance of a homogenous rock or mineral aggregate. The degree of crystallization, the size of the crystals, and the shape and interrelations of the crystals or other components all contribute to the texture of a rock. (1) |
| TUNGSTATES | A group of minerals (e.g. scheelite) in which the tungstate radical (WO4) is an important constituent. (1) |
| TWIN | A specimen that consists of two or more single crystals of the same mineral, intergrown in a definite systematic arrangement. (1) |
| ULTRABASIC ROCK | Any plutonic igneous rock (e.g. peridotite) with very low silica content (less than that of a basic rock). (1) |
| VANADATES | A group of minerals (e.g. vanadinite) in which the vanadate radical (VO4) is an important constituent. (1) |
| VEIN | A tabular or sheetlike body of mineral matter (e.g. quartz) cutting across preexisting rock (e.g. granite or gneiss). (1) |
| VESICLE | A small cavity in a volcanic rock. (1) |
| VITREOUS | Glasslike in appearance or texture. (1) |
| VOLCANISM | The movement of molten rock, by way of volcanos, fissures, vents, etc., to the earth's surface, where it cools into extrusive (volcanic) igneous rocks. (1) |
| VOLCANO | A vent or hole in the earth's crust through which magma (in the form of lava), gases, ashes, and other products escape onto the surface. (1) |
| ZEOLITES | A group of hydrated aluminosilicates of potassium, sodium, and calcium that can lose part or all of their water (reversibly) without changing crystal structure. This open structure allows the zeolites to absorb other compounds, making them commercially valuable as purifiers and water softeners. (1) |
Bibliography
- "The Audubon Society Field Guide to North American Rocks and Minerals" Charles W. Chesterman.
- "Cunningham's Encyclopedia of Crystal, Gem & Metal Magic". Scott Cunningham
- "Crystal Enlightenment" Katrina Raphaell.
