Anthracite. A shining substance like black-lead; a species of mineral charcoal. Etym., ανθραξ, anthrax, coal.
Anthracotherium. A name given to an extinct quadruped, supposed to belong to the Pachydermata, the bones of which were first found in lignite and coal of the tertiary strata. Etym., ανθραξ, anthrax, coal, and θηριον, therion, wild beast.
Anthropomorphous. Having a form resembling the human. Etym., ανθρωπος, anthropos, a man, and μορφη, morphe, form.
Antiseptic. Substances which prevent corruption in animal and vegetable matter, as common salt does, are said to be antiseptic. Etym., αντι, anti, against, and σηπω, sepo, to putrefy.
Arenaceous. Sandy. Etym., arena, sand.
Argillaceous. Clayey, composed of clay. Etym., argilla, clay.
Arragonite. A simple mineral, a variety of carbonate of lime, so called from having been first found in Aragon in Spain.
Atolls. Coral islands of an annular form, or consisting of a circular strip or ring of coral surrounding a central lagoon.
Augite. A simple mineral of a dark green, or black color, which forms a constituent part of many varieties of volcanic rocks. Name applied by Pliny to a particular mineral, from the Greek αυγη, auge, lustre.
Avalanches. Masses of snow which, being detached from great heights in the Alps, acquire enormous bulk by fresh accumulations as they descend; and when they fall into the valleys below often cause great destruction. They are also called lavanges and lavanches in the dialects of Switzerland.