#crystalline structure

• Aluminite — A rare mineral belonging to the class of hydrated aluminum sulfates, with the chemical formula Al2(SO4)(OH)4·7H2O; it occurs as earthy masses, white nodules, or chalky aggregates, formed by the alteration of aluminum-rich rocks in the presence of acidic solutions.
• Amphibolite — A regional metamorphic rock, coarse or fine-grained, structurally formed from a crystalline mixture dominated by amphiboles (especially hornblende) and plagioclase, often accompanied by accessory minerals such as quartz, garnet, or epidote. This type of geological structure forms under high temperature and pressure conditions, specific to medium to advanced metamorphic facies.
• Ariat — A rare technical term used to describe a chemical compound or a salt derived from a specific acid or a crystalline structure analyzed in applied mineralogy laboratories.
• Arsenopyrite — A masculine or neuter variant form used alternatively in technical literature to designate the iron sulfarsenic mineral (FeAsS). This crystalline compound from the sulfide class represents the most important and widespread natural source of arsenic, exhibiting an opaque metallic luster, a steel-grey color, and a monoclinic or orthorhombic crystal structure. It is frequently associated with hydrothermal deposits of gold, copper, and tin, releasing a strong garlic odor when struck or intensely heated.