Arfvedsonite (/ˈɑːrvɛdsənaɪt/[6]) or soda hornblende (partiellement obsolète) is a sodium amphibole mineral with composition: [Na][Na2][(Fe2+)4Fe3+][(OH)2|Si8O22].

It is a rather rare mineral occurring in nepheline syenite intrusions and agpaitic (peralkaline) pegmatites and granites as the Golden Horn batholith in Okanogan County, Washington (type locality for zektzerite).

Occurrences include Mont Saint-Hilaire, Quebec, Canada; the Ilímaussaq complex in Southern Greenland; and in pegmatites of the Kola Peninsula, Russia.

Its mineral association includes nepheline, albite, aegirine, riebeckite, katophorite and quartz.

[2] Arfvedsonite was discovered in 1823 and named for the Swedish chemist Johan August Arfwedson (1792–1841).