#rocks

• Geological ablation — A conceptual form or terminological variant of 'ablație', used in classical geomorphology to describe the phenomenon of removal, washing away, or baring of rocks under the action of external agents (wind, flowing waters, waves). In soil dynamics, the term emphasizes the initial transport phase of fine detrital materials before they are deposited in sedimentary basins.
• Agatine — Pertaining to agate, relating to agate, or having the appearance, texture, or structural properties of this variety of chalcedony. In a technical or mineralogical sense, it describes materials, silicated rocks, or siliceous layers that exhibit parallel bands of different colors or a finely zoned texture characteristic of semi-precious stones within the silicate class.
• Agrogeology — A branch of applied geology and agronomy that studies the link between geological structures, parent rocks, and the formation, composition, and fertility of agricultural soils. This science provides practical solutions for improving land quality by using crushed minerals and rocks as natural and ecological amendments.
• Alkalic — Containing alkali; having basic or alkaline properties; alkaline. In geology and petrography, the term describes igneous rocks or minerals rich in alkali metals (such as sodium and potassium), characterized by a specific chemical composition that influences the structure and evolution of crustal melts.
• Aldur — A scientific term or rare variant designating a specific type of granular mineral aggregate or a microcrystalline structural variety found in ancient igneous rocks. In a broader sense, the word is analyzed in comparative petrology studies to describe silicate formations resistant to thermal erosion, which develop under extreme pressure conditions in the Earth's crust.
• Algonkian — An archaic or regional geological term previously used to designate the Late Proterozoic or the final major division of the Precambrian era. As an adjective, it describes the sedimentary and metamorphic rocks formed during this primitive stage of Earth's history.
• Algonkian — The standard international orthographic variant for the geological term 'algonchian'; an obsolete geochronological division designating the Late Proterozoic or the final part of the Precambrian era. As an adjective, it characterizes sedimentary rock strata and metamorphic schists.
• Allogenous — Of a different origin, born or formed elsewhere than its current location; an element (mineral, rock fragment, population, or individual) that is foreign to the indigenous environment in which it is integrated. In geology, it defines minerals transported from the outside and deposited in a sedimentary basin, while in sociology and anthropology, it refers to population groups originating from a geographic or cultural region different from the native one.
• Alloshite — A rare mineral or complex silicate discovered within certain metamorphic rocks or hydrothermal deposits, structurally characterized by an atypical crystalline lattice and associations with micro-mineral aggregates of foreign (allogenous) origin. This geological compound is analyzed via X-ray diffraction to establish the specific pressure and temperature conditions in the earth's crust at the moment of its crystallization.
• Allotriomorphic — Relating to minerals or crystalline components of an igneous rock: not presenting its own geometric faces or a regular native external shape, because its structural development was limited and constrained by the free spaces remaining between crystals formed earlier during magma solidification.
• Alunitization — A geological process of acid hydrothermal alteration of volcanic or magmatic rocks rich in feldspars, under the action of ascending solutions charged with sulfuric acid; the act of transforming into alunite. This structural phenomenon leads to the replacement of primary minerals with alunite, quartz, and kaolinite, constituting a valuable indicator in geological prospecting for metalliferous deposits.
• Ammonite — A fossil marine cephalopod mollusk from the Ammonoidea subclass, characterized by an external, planospiral, and chambered calcareous shell, which lived from the Devonian period until the end of the Cretaceous. The fossils of these organisms are widely used in stratigraphical geology as index fossils for the precise dating of sedimentary rock layers from the Mesozoic era.
• Anatexis — A deep geological process of partial or total melting of pre-existing rocks within the lower crust (metamorphic or igneous) under the action of extremely high temperatures and pressures. Representing the ultimate stage of regional metamorphism (ultrametamorphism), anatexis leads to the formation of secondary granitic magmas and mixed rocks called migmatites, playing a fundamental role in the recycling and structural evolution of the lithosphere.
• Andalusite — A structural mineral consisting of aluminum silicate that crystallizes in the orthorhombic system, being characteristic of metamorphic rocks formed under low pressures and medium to high temperatures. Due to its exceptional thermal resistance and high melting point, andalusite is widely used in industry as a refractory material for lining metallurgical furnaces, while its transparent and colored varieties are sometimes used as gemstones in jewelry.
• Andalusite — A linguistic variant or synonymous regional form of the standard term 'andaluzit', designating the natural aluminum silicate that crystallizes in the orthorhombic system. It is sometimes used in older geological treatises or technical translations to describe the rock or refractory mineral mass composed predominantly of this crystallized silicate type.
• Andesine — A mineral belonging to the silicate class, specifically an intermediate variety of plagioclase feldspar, structurally defined by a specific chemical ratio between albite and anorthite (between 30% and 50% anorthite). It is a common constituent of intermediate igneous rocks, such as andesites and diorites, receiving its name from the Andes Mountains, where it was initially identified and abundantly described.
• Andesine — A mineral belonging to the plagioclase feldspar group, consisting of an isomorphic mixture of albite and anorthite in determined proportions, being a natural silicate of aluminum, calcium, and sodium. It crystallizes in the triclinic system and represents an essential and diagnostic component in the structure of intermediate igneous rocks, its name being linked to its abundant occurrence in the Andes mountain range.
• Andesitic — Belonging to andesite, relating to andesite, or having the composition, structure, and characteristics specific to this effusive igneous rock. In petrography, it describes magmas, lavas, tuffs, or volcanic flows with an intermediate silica content, characteristic of tectonic subduction zones.
• Anemoclastics — Clastic rocks, mineral fragments, or sedimentary deposits fragmented, crushed, and structurally shaped by the mechanical action of erosion, abrasion, or transport carried out by the wind (aeolian processes). As an adjective, it describes geological structures or debris formed via wind deflation and corrasion.
• Anorthite — A mineral belonging to the silicate class, representing the pure calcium endmember of the plagioclase feldspar isomorphic series (calcium aluminum silicate). It crystallizes in the triclinic system, features a white, grayish, or reddish color, and is a common structural constituent in basic and ultrabasic igneous rocks (such as gabbros and basalts), as well as in some metamorphic rocks or meteoritic materials.