#metamorphic rocks

• 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.
• 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.
• 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.