Macaronesia, Océano Atlántico, Mineralogy, Azores, cations, potassium, sodium, volcanic rocks, Terceira, Atlantic Ocean Islands, igneous rocks, metals, silicates, pyroclastics, chemical composition, crystal chemistry, Terceira Island, alkali metals, alkali syenites, Caldeira-Castelinho Ignimbrite Formation, dalyite, electron probe data, formula, ignimbrite,...